JP2003162023A - Solid dispersion material, method for storing the same and heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid dispersion material of a photographic compound excellent in the stability with time, to provide a method for storing the material, and to provide a heat developable photosensitive material having an excellent coating surface state and favorable photographic sensitivity and density. <P>SOLUTION: The solid dispersion material of a photographic compound contains a dispersoid consisting of organic compounds and a dispersion medium. The average settling velocity (v<SB>25</SB>) of the dispersoid expressed by formula (1): v<SB>25</SB>=2r<SP>2</SP>g(ρs<SB>25</SB>-ρ<SB>25</SB>)/9η<SB>25</SB>at 25°C is ≤5.0×10<SP>-6</SP>mm/sec. The method for storing the above material is provided. The above solid dispersion material is used for the heat developable photosensitive material or the like. In formula (1), r represents the median diameter of the dispersoid, g is the gravitational acceleration, ρs<SB>25</SB>is the specific gravity of the dispersoid at 25°C, ρ<SB>25</SB>is the specific gravity of the dispersion medium at 25°C and η<SB>25</SB>is the viscosity of the dispersion material at 25°C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid dispersion, a method for storing the same, and a photothermographic material (hereinafter sometimes referred to as "photosensitive material"). More specifically, it has excellent stability over time. The present invention relates to a solid dispersion of a photographically useful compound, a storage method thereof, and a photothermographic material suitable for medical diagnosis, industrial photography, printing, and COM, which uses the solid dispersion.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand in the medical field to reduce the amount of processing waste liquid from the viewpoint of environmental protection and space saving.
Therefore, it can be efficiently exposed by a laser image setter or a laser imager, and can form a clear black image having high resolution and sharpness. There is a need for technology relating to developed photographic materials. These light-sensitive heat-developable photographic materials can provide customers with a heat-development processing system that eliminates the use of solution-type processing chemicals and is simpler and does not damage the environment.

Although there are similar demands in the field of general image forming materials, since medical images are required to be minutely drawn, high image quality excellent in sharpness and graininess is required, and diagnosis is easy. From the viewpoint of, there is a feature that a cold black tone image is preferred.
Currently, ink jet printers, electrophotographic pigments,
Various hard copy systems using dyes are distributed as general image forming systems, but none are satisfactory as medical image output systems.

In order to meet such demands, thermal image forming systems utilizing organic silver salts are disclosed in, for example, US Pat. Nos. 3,152,904, 3457075 and B. "The Thermally Processed Silver System" by Shelly
ssed Silver Systems "(Imaging Processes and Materials (Im
aging Processes and Mater
ials) Neblette 8th Edition, Sturge (St
urge), V. Wallworth
h), A. Edited by Shepp, page 2, 19
1996). In particular, the photothermographic material is
Generally, a catalytically active amount of a photocatalyst (eg, silver halide), a reducing agent, a reducible silver salt (eg, organic silver salt), and optionally a toning agent for controlling the color tone of silver are dispersed in a binder matrix. It has a photosensitive layer. The photothermographic material is heated to a high temperature (for example, 80 ° C. or higher) after image exposure,
A black silver image is formed by a redox reaction between a silver halide or a reducible silver salt (which functions as an oxidizing agent) and a reducing agent. The redox reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. Therefore, a black silver image is formed in the exposed area. The above technique is described in US Pat. No. 2,910,377, Japanese Patent Publication No. 43-4.
Fuji Medical Dry Imager FM-DP L has been disclosed as a medical image forming system using a photothermographic material, which is disclosed in many documents including Japanese Patent No. 924.

On the other hand, a method of introducing an additive such as a reducing agent, a toning agent or an antifoggant necessary for a thermal image-sensitive material is an aqueous solution,
There are various methods such as emulsions and solid dispersions, and in any case, it is required that a physically stable state be maintained during storage. However, in the case of using an emulsion or a solid dispersion, there is a problem that aggregation may occur during storage, a change in particle size due to aging, a precipitate may occur, and the like. In order to remove such aggregates, particle size changes or sediments, the solid dispersion can be filtered, but the filterability may deteriorate, and during the production of the photothermographic material, filter clogging may occur. Therefore, there is a problem that the manufacturing suitability may be deteriorated. Further, when such a solid dispersion is used without being filtered, there is a problem that variations in photographic sensitivity and density occur due to deterioration of the coated surface state of the photothermographic material. With respect to the stability over time, it was necessary to impart sufficient physical stability.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and achieve the following objects. That is, the present invention provides a solid dispersion of a photographically useful compound having excellent stability over time, a method for storing the same, and a photothermographic material having excellent coating surface state, good photographic sensitivity and density. To aim.

[0007]

[In Formula (1), r is the median diameter of the dispersoid, g is the gravitational acceleration, ρs ₂₅ is the specific gravity of the dispersoid at 25 ° C., ρ ₂₅ is the specific gravity of the dispersion medium at 25 ° C., and η ₂₅ is the dispersion at 25 ° C. Represents the viscosity of. ]

<2> The solid dispersion of the photographically useful compound according to <1>, wherein the dispersoid in the formula (1) has a specific gravity (ρs ₂₅ ) of 1.1 or more.

<3> The organic compound is a solid dispersion of the photographically useful compound according to <1> or <2>, which is a polyhalogen compound.

<4> A method for storing a solid dispersion of a photographically useful compound, comprising storing the solid dispersion of the photographically useful compound according to any one of <1> to <3> at room temperature. is there.

<5> A solid dispersion of a photographically useful compound containing a dispersoid composed of an organic compound and a dispersion medium,
A solid dispersion of a photographically useful compound, characterized in that the dispersoid has an average sedimentation velocity (v ₁₀ ) represented by the following formula (2) at 10 ° C. of 2.5 × 10 ⁻⁶ mm / sec or less. Is. In equation ^{_{(2) v 10 = 2r 2}} g (ρs 10 -ρ 10) / 9η 10 [formula (2), r is the median diameter of the dispersoid, g is the gravitational acceleration, .rho.s ₁₀ specific gravity of the dispersoid at 10 ° C. , Ρ
₁₀ represents the specific gravity of the dispersion medium at 10 ° C, and η ₁₀ represents the viscosity of the dispersion at 10 ° C. ]

<6> The solid dispersion of the photographically useful compound according to <5>, wherein the specific gravity (ρs ₁₀ ) of the dispersion medium in the formula (2) is 1.1 or more.

<7> The organic compound is a solid dispersion of the photographically useful compound according to <5> or <6>, which is a polyhalogen compound.

<8> A method for storing a solid dispersion of a photographically useful compound, comprising storing the solid dispersion of the photographically useful compound according to any one of <5> to <7> under refrigeration. is there.

<9> A photothermographic material having on a support at least one layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions, and a binder, The layer and / or another layer provided on the support is coated and dried with a coating solution containing at least one solid dispersion of a photographically useful compound containing a dispersoid composed of an organic compound and a dispersion medium. 25 ° C. of the dispersoid represented by the following formula (1)
Average sedimentation velocity (v ₂₅ ) at 5.0 × 10 ^-6 mm
It is a photothermographic material characterized by being below / sec. In the formula ^{_{(1) v 25 = 2r 2}} g (ρs 25 -ρ 25) / 9η 25 [formula (1), r is the median diameter of the dispersoid, g is the gravitational acceleration, .rho.s ₂₅ specific gravity of the dispersoid at 25 ° C. , Ρ
₂₅ represents the specific gravity of the dispersion medium at 25 ° C., and η ₂₅ represents the viscosity of the dispersion at 25 ° C. ]

<10> The photothermographic material according to <9>, wherein the dispersoid in the formula (1) has a specific gravity (ρs ₂₅ ) of 1.1 or more.

<11> In a photothermographic material having at least one layer on a support, which contains at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions and a binder, said layer And / or another layer provided on the support is coated and dried with a coating solution containing at least one solid dispersion of a photographically useful compound containing a dispersoid composed of an organic compound and a dispersion medium. 10 ° C. of the dispersoid represented by the following formula (2).
Average sedimentation velocity (v ₁₀ ) at 2.5 × 10 ⁻⁶ mm
It is a photothermographic material characterized by being below / sec. In equation ^{_{(2) v 10 = 2r 2}} g (ρs 10 -ρ 10) / 9η 10 [formula (2), r is the median diameter of the dispersoid, g is the gravitational acceleration, .rho.s ₁₀ specific gravity of the dispersoid at 10 ° C. , Ρ
₁₀ represents the specific gravity of the dispersion medium at 10 ° C, and η ₁₀ represents the viscosity of the dispersion at 10 ° C. ]

<12> The photothermographic material according to <11>, wherein the specific gravity (ρs ₁₀ ) of the dispersoid in the formula (2) is 1.1 or more.

<13> The photothermographic material according to any one of <9> to <12>, wherein the organic compound is a polyhalogen compound.

<14> The above-mentioned <9>, wherein the binder is a latex and the coating liquid is an aqueous coating liquid.
To <13>.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. [Solid Dispersion and Method for Preserving the Same] The solid dispersion of the present invention is a solid dispersion of a photographically useful compound containing a dispersoid composed of an organic compound and a dispersion medium. ) Average sedimentation rate at 25 ° C. (v ₂₅ )
Is 5.0 × 10 ⁻⁶ mm / sec or less, which is a solid dispersion of a photographically useful compound (hereinafter sometimes simply referred to as “solid dispersion”). Equation ^{_{(1) v 25 = 2r 2}} g (ρs 25 -ρ 25) / 9η 25

In the above formula (1), r is the median diameter of the dispersoid, g is the acceleration of gravity, ρs ₂₅ is the specific gravity of the dispersoid at 25 ° C., ρ ₂₅ is the specific gravity of the dispersion medium at 25 ° C., η ₂₅
Represents the viscosity of the dispersion at 25 ° C.

The average sedimentation rate (v of the dispersoid contained in the solid dispersion of the present invention at 25 ° C. represented by the above formula (1) (v
₂₅ ) is 5.0 × 10 ⁻⁶ mm / sec or less, preferably 3.0 × 10 ⁻⁶ mm / sec or less.

In the solid dispersion of the present invention, the dispersoid contained in the solid dispersion has an average sedimentation rate (v ₂₅ ) represented by the above formula (1) of 5.0 × 10 ^-6. Those exhibiting mm / sec or less are preferably stored at room temperature.
In the present specification, storage at room temperature refers to storage in a state in which the temperature is not specified, but is 15 to 35 ° C.
More preferred is storage within the range.

The solid dispersion of the present invention is a solid dispersion of a photographically useful compound containing a dispersoid composed of an organic compound and a dispersion medium, and the dispersoid is represented by the following formula (2). The average sedimentation rate (v ₁₀ ) at 10 ° C. is 2.5 × 1
It is characterized by being a solid dispersion of a photographically useful compound characterized in that it is 0 ^-6 mm / sec or less. Equation ^{_{(2) v 10 = 2r 2}} g (ρs 10 -ρ 10) / 9η 10

In the above formula (2), r is the median diameter of the dispersoid, g is the gravitational acceleration, ρs ₁₀ is the specific gravity of the dispersoid at 10 ° C., ρ ₁₀ is the specific gravity of the dispersion medium at 10 ° C., η ₁₀
Represents the viscosity of the dispersion at 10 ° C.

In the solid dispersion of the present invention, the average sedimentation rate (v ₁₀ ) at 10 ° C. represented by the above formula (2).
Is 2.5 × 10 ⁻⁶ mm / sec or less, 1.0 × 1
It is preferably 0 ^-6 mm / sec or less.

In the solid dispersion of the present invention, the average settling rate (v ₁₀ ) of the dispersoid contained in the solid dispersion represented by the above formula (2) is 2.5 × 10 ^-6. Those exhibiting mm / sec or less are preferably stored under refrigeration.
In the present specification, storage under refrigeration refers to storage at 15 ° C or lower, and storage within 4 to 10 ° C is more preferable.

When the average sedimentation velocity (v ₂₅ ) of the dispersoid contained in the solid dispersion of the present invention is 5.0 × 10 ⁻⁶ mm / sec or more, and / or the average sedimentation velocity (v ₁₀ ). But,
When it is 2.5 × 10 ⁻⁶ mm / sec, problems may occur with respect to the stability over time of the solid dispersion, particularly the sedimentation property. That is, the concentration of the upper part of the storage container may decrease after a lapse of time, or a precipitate may be formed on the bottom of the storage container.

The details of the median diameter (r) of the dispersoid, the specific gravity of the dispersoid (ρs), the specific gravity of the dispersion medium (ρ), and the viscosity (η) of the solid dispersion in the solid dispersion of the present invention will be described below. To do.

-Median diameter (r) -The median diameter (r) of the dispersoid can be determined by various methods [for example,
Light scattering particle size distribution measurement (for example, LA-9 manufactured by Horiba Ltd.)
20), particle size distribution measurement by ultrasonic waves or electromagnetic waves (for example,
Nippon Luft Co., Ltd., ultrasonic type particle size distribution measuring device DT-
1200, Nikkiso Co., Ltd., Microtrack UP
A), a particle size distribution measuring method using centrifugal force (for example, a disk centrifugal particle size distribution measuring device CP manufactured by Nippon Luft Co., Ltd.
S), particle size distribution measurement using electric resistance (manufactured by Sysmex Corp., electric resistance particle size distribution measurement device), particle size distribution measurement by particle image (Central Scientific Trading Co., Ltd. particle image analysis device), turbidity Particle size distribution measurement (manufactured by Shimadzu Corporation, turbidity / particle diameter measuring device), etc., but the median diameter (r) in the present invention is light scattering manufactured by Shimadzu Corporation. Particle size distribution analyzer SALD-2000 (refractive index parameter is
The median diameter measured in 1.70-0.1i) is used.

The median diameter (r) of the dispersoid in the present invention is preferably 1.5 μm or less,
0.05 μm or more and 1.0 μm or less is more preferable, and 0.
It is more preferably 1 or more and 0.7 μm or less.

-Specific gravity of dispersoid (ρs) and specific gravity of dispersion medium (ρ) -Specific gravity of dispersoid (ρs) is represented by the following formula (3). Specific gravity of solid dispersion (ρd), dispersant solution It is calculated using the value calculated from the specific gravity (ρb) and the composition of the solid dispersion. In the present invention, v in the above formula (1)
When calculating the ₂₅ uses a .rho.s ₂₅ and [rho _25, respectively,
When calculating v ₁₀ in the equation (2), ρs ₁₀ and ρ ₁₀ are used. Here, .rho.s ₂₅ and .rho.s ₁₀ are the specific gravity of the dispersoid at 25 ° C. and 10 ° C. respectively, [rho ₂₅
And ρ ₁₀ represent the specific gravity of the dispersion medium at 25 ° C. and 10 ° C., respectively.

Equation (3) ρs = Cs / (1 / ρd- (1-Cs-Cb) / ρ-C
b / ρb) where Cs is the dispersoid concentration (weight fraction), Cb is the concentration of the dispersant (weight fraction), ρd is the specific gravity of the solid dispersion, and ρb
Is the specific gravity of the dispersant solution. In the formula (3), ρb is represented by the following formula (4), and is calculated using the specific gravity (ρh) of the dispersant solution, the specific gravity (ρ) of the dispersion medium, and the value calculated from the composition of the dispersant. To be done.

Formula (4) ρb = Cb / (1 / ρh- (1-Cb) / ρ) where ρh is the specific gravity of the dispersant solution and ρ is the specific gravity of the dispersion medium.

The specific gravities of the solid dispersion, the dispersant solution and the dispersion medium can be measured by various methods (eg, measurement with a standard pycnometer, flotation type measurement pycnometer, natural frequency type density pycnometer, etc.). However, in the present invention, the specific gravity measured by a standard specific gravity meter (manufactured by Nippon Keiki Co., Ltd.) is used.

The specific gravity (ρs) of the dispersoid in the present invention
Is preferably 1.1 or more, and 1.1 or more and 4.0 or less
More preferably, 1.5 or more and 3.0 or less are more preferable.
Yes. That is, in both cases of 25 ° C and 10 ° C,
Specific gravity of dispersoid (ρs_{twenty five}And ρs _Ten) Is within the above range
Preferably. Also, as the specific gravity (ρ) of the dispersion medium
Is preferably 0.8 or more and 1.2 or less, and 0.9 or more and 1.
1 or less is more preferable, and 0.98 or more and 1.05 or less is
Preferred. That is, in the case of both 25 ℃ and 10 ℃
Also, the specific gravity of the dispersion medium (ρ_{twenty five}And ρ _Ten) Is the above range
It is preferably within. Furthermore, ρs ≧ ρ
Is preferred.

-Viscosity (η) -The viscosity (η) of the solid dispersion in the present invention can be measured by various methods (for example, B-type viscometer, E-type viscometer, vibration type viscometer,
Etc.), but in the present invention, η is a B-type viscometer (manufactured by Tokimec Co., Ltd., DV-M-
The viscosity measured in B) is used. In the present invention, when calculating v ₂₅ in the formula (1), η ₂₅
When calculating v ₁₀ in the equation (2) using
η ₁₀ is used. η ₂₅ and η ₁₀ are 25 ° C and 1 respectively
It represents the viscosity at 0 ° C.

In the solid dispersion of the present invention, η ₂₅ is 0.
05 Pa · s or more is preferable, and 0.08 Pa is preferable.
-S or more and 0.5 Pa-s or less is more preferable, and 0.09
Pa · s or more and 0.30 cPa · s or less is more preferable. Further, η ₁₀ is preferably 0.1 Pa · s or more, and 0.
More preferably 14 Pa · s or more and 0.5 Pa · s or less,
More preferably, it is 0.16 Pa · s or more and 0.30 Pa · s or less.

When measuring the specific gravity and the viscosity of the solid dispersion, it is necessary to remove the bubbles in the solid dispersion because accurate values of the specific gravity and the viscosity cannot be obtained if there are bubbles in the solid dispersion. . As a method for removing bubbles, for example, there are various methods such as ultrasonic defoaming, vacuum defoaming, vacuum ultrasonic defoaming, centrifugal defoaming, and defoaming method utilizing viscosity decrease due to temperature increase. In the invention, it is preferable to remove bubbles by the vacuum ultrasonic defoaming method.

The median diameter (r), the specific gravity (ρs) and the viscosity (η) of the dispersoid in the solid dispersion of the present invention are the dispersion conditions, dispersion time,
It can be arbitrarily set by changing the dispersant concentration and the dispersion concentration.

As the dispersoid composed of an organic compound contained in the solid dispersion of the present invention and having a specific gravity of 1.1 or more, there are various organic compounds, but a reducing agent, a development accelerator and a hydrogen bond. Suitable examples thereof include a photosensitive compound, an antifoggant, a polyhalogen compound, a toning agent, and other photographic compounds. Among them, the solid dispersion of the present invention is preferably a reducing agent, a development accelerator, a hydrogen bonding compound or a polyhalogen compound, and most preferably a polyhalogen compound. Further, the dispersoid in the present invention is preferably a compound which is hardly soluble in the dispersion medium.

Examples of the dispersion medium contained in the solid dispersion of the present invention include water and organic solvents (methanol, ethanol, isopropyl alcohol, methyl cellosolobe, ethyl cellosolve, dimethylformamide, ethyl acetate, etc.) and mixtures thereof. The dispersion medium in the present invention is preferably water containing 30% by mass or less of an organic solvent or water containing no organic solvent, and more preferably water containing 10% by mass or less of an organic solvent. Most preferably, it is water containing an organic solvent of not more than%, or water containing no organic solvent.

The solid dispersion of the present invention can be produced by using a media type disperser which grinds with a medium, a high speed stirring type disperser having a large shearing force, a disperser which gives high intensity ultrasonic energy, and the like. , For example, ball mill,
A colloid mill, a sand mill, a homogenizer, a capillary type emulsifying device, a liquid siren, an electromagnetic distortion type ultrasonic generator, an emulsifying device having a Paulman whistle, and the like can be used. Among these, media dispersion using a media type disperser is preferable, and water-based media dispersion is more preferable.

As a method of media dispersion, an organic compound moistened with water or an organic solvent called a dispersoid powder or wet cake is made into an aqueous slurry, and a known pulverizer such as a ball mill, a colloid mill, a vibrating ball mill or a vertical sand mill is used. , Roller mill, pin mill, co-ball mill,
By mechanical force in the presence of dispersing media (steel balls, ceramic balls, glass beads, alumina beads, zirconia silicate beads, zirconia beads, Ottawa sands, etc.) using a caddy mill, vertical sand mill, horizontal sand mill, or attritor. Examples thereof include a method of pulverizing and dispersing. Among these, a ball mill, a colloid mill, a vertical sand mill and a horizontal sand mill are preferably used, and a vertical sand mill and a horizontal sand mill are more preferable.

There are various types of horizontal sand mills, for example, Ultra Visco Mill (UVM; manufactured by AIMEX Co., Ltd.), Agitator Mill LMK (manufactured by Ajisawa Co., Ltd.), Dyno Mill (manufactured by Shinmaru Enterprise Co., Ltd.). ) And the like. Among these, Ultra Viscomil (UVM; manufactured by AIMEX Co., Ltd.) is preferable.

As the dispersion medium (beads), glass beads, alumina beads, zirconia silicate beads and zirconia beads are preferable, and zirconia silicate beads and zirconia beads are more preferable. There are various sizes of dispersion media, but the average diameter is preferably 0.3 mm to 5 mm, more preferably 0.3 mm to 3 mm, and even more preferably 0.
3 mm to 2 mm, 0.3 mm, 0.5 mm, 1.
The one having 0 mm or 2.0 mm is most preferably used. These dispersion media may be used alone or as a mixture. When mixed and used, the mixing ratio can be set arbitrarily.

The dispersant (protective colloid) is generally sent to the disperser as a slurry, but the dispersoid (for example, a powder of a photographically useful organic compound or an organic compound in the form of a wet cake) is dispersed prior to the dispersing operation. It is preferable to make the dispersion medium into a slurry (preliminary dispersion). Known means for making a slurry (for example, mixing with propeller blades, high speed mixer, homogenizer, high speed impact mill, Banbury mixer, homomixer, kneader, ball mill, vibrating ball mill, planetary ball mill, attritor, sand mill, bead mill, colloid Mill, jet mill, roller mill, tron mill, high speed stone mill, etc.) can be used. In addition to mechanical dispersion, the pH may be changed in the presence of a dispersion aid to form fine particles. At this time, an organic solvent may be used as a solvent used for the coarse dispersion, and the organic solvent is usually removed after the completion of microparticulation. In the present invention, a method is preferred in which the dispersoid is gradually added to the dispersion medium solution and mixed with a propeller blade.

A surfactant may be used for dispersing the medium. As the surfactant, any of nonionic and ionic (anion, cation, betaine) can be used.
As the nonionic surfactant, polyoxyethylene,
Examples thereof include surfactants having polyoxypropylene, polyoxybutylene, polyglycidyl or sorbitan as a nonionic hydrophilic group. Specifically, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, Examples thereof include polyglycerin fatty acid ester, fatty acid diethanolamide and triethanolamine fatty acid partial ester.

Examples of anionic surfactants include carboxylates, sulfates, sulfonates and phosphate ester salts. Typical examples include fatty acid salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfonates, α-olefin sulfonates, dialkyl sulfosuccinates, α-sulfonated fatty acid salts, N-methyl-N. -Oleyl taurine, petroleum sulfonate, alkyl sulfate, sulfated oil, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphate, poly Examples thereof include oxyethylene alkyl ether phosphates and naphthalene sulfonate formaldehyde condensates.

Examples of the cationic surfactants include amine salts, quaternary ammonium salts, pyridinium salts and the like. Among these, primary to tertiary fatty amine salts,
Quaternary ammonium salts (tetraalkylammonium salt, trialkylbenzylammonium salt, alkylpyridinium salt, alkylimidazolium salt, etc.) are preferred.

Examples of betaine-based surfactants include carboxybetaine and sulfobetaine. Among these, N-trialkyl-N-carboxymethylammonium betaine and N-trialkyl-N-sulfoalkyleneammonium betaine. Etc. are preferred. These surfactants are described in "Applications of Surfactants" (Koshobo, Takao Karime, published September 1, 1980). Particularly preferred as the surfactant in the present invention is an anionic surfactant having a sulfonic acid group.

Specific examples of the surfactant will be shown below, but the surfactant usable in the present invention is not limited to these. (Here, -C ₆ H ₄ - represents a phenylene group). WA-1: Sodium dodecylbenzene sulfonate WA-2: Sodium tri (isopropyl) naphthalene sulfonate WA-3: Sodium tri (isobutyl) naphthalene sulfonate WA-4: Sodium dodecyl sulfate WA-5: α-sulfa succinate di ( 2-ethylhexyl) ester sodium salt _{WA-6: C 8 H 17} -C 6 H 4 - (CH 2 CH 2 O) 3 (C
_{H 2) 2 SO 3 K WA} -7: cetyltrimethylammonium chloride _{WA-8: C 11 H 23} CONHCH 2 CH 2 N + (CH 3)
₂ -CH ₂ COO ^-

In the dispersion operation, it is preferable to disperse the dispersoid in the presence of an aqueous solvent-soluble dispersant (protective colloid). A hydrophilic colloid can be used as the dispersant. For example, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole, maleic acid copolymer, maleic acid monoester copolymer, acrylomethylpropanesulfonic acid copolymer, polyvinylpyrazole, Various synthetic hydrophilic polymeric substances such as polyethylene glycol, polypropylene glycol, etc., such as single or copolymers, semisynthetic anionic polymers such as carboxymethyl starch, carboxymethyl cellulose, anionic polymers such as alginic acid, pectic acid, etc. 7-3507
53, gelatin derivatives, graft polymers of gelatin and other polymers, proteins such as albumin and casein, cellulose derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose, cellulose sulfates, sodium alginate and starch. A sugar derivative such as a derivative, polyvinyl alcohol, a polyvinyl alcohol partial acetal, or a naturally occurring polymer compound such as gelatin can be appropriately selected and used. The dispersants may be used alone or in combination of two or more.

As the dispersant in the present invention, polyethylene glycol, polypropylene glycol, polyvinyl alcohols and water-soluble cellulose derivatives are preferably used, and polyvinyl alcohols are particularly preferable.

The following compounds may be mentioned as polyvinyl alcohols (PVA). As a completely saponified product, PVA-105 [polyvinyl alcohol (P
VA) content 94.0 mass% or more, saponification degree 98.5 ±
0.5 mol%, sodium acetate content 1.5 mass% or less, volatile content 5.0 mass% or less, viscosity (4 mass%, 20
℃) 5.6 ± 0.4 Pa · s], PVA-110 [PV
A content 94.0 mass%, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.5 mass%, volatile matter 5.
0 mass%, viscosity (4 mass%, 20 ° C) 11.0 ± 0.8
Pa · s], PVA-117 [PVA content 94.0 mass%, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity ( Four
Mass%, 20 ° C.) 28.0 ± 3.0 Pa · s], PVA
-117H [PVA content 93.5 mass%, saponification degree 9
9.6 ± 0.3 mol%, sodium acetate content 1.85
Mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20
C) 29.0 ± 3.0 Pa · s], PVA-120 [P
VA content 94.0 mass%, saponification degree 98.5 ± 0.5
Mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 39.5 ±
4.5 Pa · s], PVA-124 [PVA content 9
4.0% by mass, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.0% by mass, volatile content 5.0% by mass,
Viscosity (4 mass%, 20 ° C) 60.0 ± 6.0 Pa
s], PVA-124H [PVA content 93.5 mass%, saponification degree 99.6 ± 0.3 mol%, sodium acetate content 1.85 mass%, volatile matter 5.0 mass%, viscosity (4
Mass%, 20 ° C.) 61.0 ± 6.0 Pa · s], PVA
-CS [PVA content 94.0 mass%, saponification degree 97.
5 ± 0.5 mol%, sodium acetate content 1.0% by mass, volatile content 5.0% by mass, viscosity (4% by mass, 20 ° C.) 2
7.5 ± 3.0 Pa · s], PVA-CST [PVA content 94.0 mass%, saponification degree 96.0 ± 0.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5. 0
Mass%, viscosity (4 mass%, 20 ° C.) 27.0 ± 3.0P
a · s], PVA-HC [PVA content 90.0 mass%, saponification degree 99.85 mol% or more, sodium acetate content 2.5 mass%, volatile matter 8.5 mass%, viscosity (4 mass% , 20 ° C.) 25.0 ± 3.5 Pa · s] (all of these are trade names of Kuraray Co., Ltd.) and the like.

As a partially saponified product, PVA-203
[PVA content 94.0 mass%, saponification degree 88.0 ±
1.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 3.4 ±
0.2 Pa · s], PVA-204 [PVA content rate 9
4.0% by mass, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0% by mass, volatile content 5.0% by mass,
Viscosity (4% by mass, 20 ° C.) 3.9 ± 0.3 Pa · s],
PVA-205 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.
0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20
C) 5.0 ± 0.4 Pa · s], PVA-210 [PV
A content 94.0% by mass, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatile matter 5.
0 mass%, viscosity (4 mass%, 20 ° C.) 9.0 ± 1.0 P
a · s], PVA-217 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity ( 4% by mass, 20 ° C.) 22.5 ± 2.0 Pa · s], PVA-
220 [PVA content 94.0 mass%, saponification degree 88.
0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 3
0.0 ± 3.0 Pa · s], PVA-224 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5. 0
Mass%, viscosity (4 mass%, 20 ° C.) 44.0 ± 4.0 P
a · s], PVA-228 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0 mass%, volatile content 5.0 mass%, viscosity ( 4% by mass, 20 ° C.) 65.0 ± 5.0 Pa · s], PVA-
235 [PVA content 94.0 mass%, saponification degree 88.
0 ± 1.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 9
5.0 ± 15.0 Pa · s], PVA-217EE [P
VA content 94.0 mass%, saponification degree 88.0 ± 1.0
Mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 23.0 ±
3.0 Pa · s], PVA-217E [PVA content rate 9
4.0% by mass, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatile content 5.0% by mass,
Viscosity (4 mass%, 20 ° C) 23.0 ± 3.0Pa ・
s], PVA-220E [PVA content 94.0 mass%, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass %, 20 ° C.) 31.0 ± 4.0 Pa · s], PVA-
224E [PVA content 94.0 mass%, saponification degree 8
8.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.)
45.0 ± 5.0 Pa · s], PVA-403 [PVA
Content 94.0 mass%, saponification degree 80.0 ± 1.5 mol%, sodium acetate content 1.0 mass%, volatile content 5.0
Mass%, viscosity (4 mass%, 20 ° C.) 3.1 ± 0.3 Pa
.S], PVA-405 [PVA content 94.0 mass%, saponification degree 81.5 ± 1.5 mol%, sodium acetate content 1.0 mass%, volatile content 5.0 mass%, viscosity (4 Mass%, 20 ° C.) 4.8 ± 0.4 Pa · s], PVA-4
20 [PVA content 94.0 mass%, saponification degree 79.5
± 1.5 mol%, sodium acetate content 1.0 mass%,
Volatile content 5.0 mass%], PVA-613 [PVA content 94.0 mass%, saponification degree 93.5 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile 5.0 mass. %, Viscosity (4 mass%, 20 ° C.) 16.5 ± 2.0 Pa.
s], L-8 [PVA content 96.0 mass%, saponification degree 71.0 ± 1.5 mol%, sodium acetate content 1.0]
Mass% (ash content), volatile content 3.0 mass%, viscosity (4 mass%, 20 ° C.) 5.4 ± 0.4 Pa · s] (all of these are trade names of Kuraray Co., Ltd.) and the like. To be The above measured values are obtained according to JIS K-6726-1977.

For the modified polyvinyl alcohol,
“Poval” can be used those described in Koichi Nagano et al. As denaturation, cation,
There are modifications with anions, -SH compounds, alkylthio compounds, and silanols. Examples of the modified polyvinyl alcohol (modified PVA) include C-118 and C-C as C polymers.
-318, C-318-2A, C-506 (all above are trade names of Kuraray Co., Ltd.), H as HL polymer
L-12E, HL-1203 (all above are trade names of Kuraray Co., Ltd.), HM-03 as HM polymer,
HM-N-03 (all of which are trade names of Kuraray Co., Ltd.), KL-118, KL-318 as K polymer,
KL-506, KM-118T, KM-618 (above,
All of them are trade names of Kuraray Co., Ltd., M-polymers are M-115 (trade names of Kuraray Co., Ltd.), MP polymers are MP-102, MP-202, MP-203 (all of them are Kuraray ( Trade name), R-1130, R-2105, R-2130 (all above are trade names of Kuraray Co., Ltd.) as R polymer, and V-2250 (Kuraray Co., Ltd.) as V polymer. Product name) etc. In the present invention, among these modified polyvinyl alcohols, partially saponified polyvinyl alcohol, K polymer and MP polymer are preferable, and MP polymer is particularly preferable.

These dispersants are preferably used in combination with the above-mentioned surfactant. Examples of the combined use include sodium dodecylbenzenesulfonate / PVA-203 and sodium dodecylbenzenesulfonate / PVA-20.
5, sodium dodecylbenzene sulfonate / PVA-
217, sodium dodecylbenzene sulfonate / MP
-203, sodium dodecylbenzene sulfonate / K
M-618, sodium tri (isopropyl) naphthalene sulfonate / PVA-203, tri (isopropyl)
Sodium naphthalene sulfonate / PVA-205, sodium tri (isopropyl) naphthalene sulfonate /
PVA-217, sodium tri (isopropyl) naphthalene sulfonate / MP-203, sodium tri (isopropyl) naphthalene sulfonate / MP-103,
Etc. Among these, sodium dodecylbenzene sulfonate / PVA-205, sodium tri (isopropyl) naphthalene sulfonate / PVA-21
7, sodium tri (isopropyl) naphthalene sulfonate / MP-203 is particularly preferred.

In the method for producing a solid dispersion of the present invention,
After the media dispersion described in the specification of Japanese Patent Application No. 2000-240658, heat treatment is preferable.

An antifoaming agent may be added to the solid dispersion of the present invention for the purpose of facilitating handling during dispersion. Examples of the defoaming agent include higher alcohols, fatty acid esters, phosphoric acid esters, polypropylene glycol, silicone oil emulsions and the like. Specific examples include pionin (Takemoto oil), Nissan Dishome (Nippon oil), N
UC Silicone (Nippon Unicar), Shin-Etsu Chemical KM Series (Shin-Etsu Chemical), Pluronic Series (Pluronic), surfynol Series (Air Products)
Etc. Also, a small amount of an organic solvent such as methanol or ethanol may be used. All of these compounds can be easily obtained as commercial products. Among these, Pluronic series, surfynol series, and methanol are preferable, and surfynol 104E
Is more preferable.

The amount of the defoaming agent added is preferably 0.1 g to 10 g, more preferably 0.5 g to 5 g, still more preferably 0.5 g to 3 g, per kg of the dispersion.

To the solid dispersion of the organic compound of the present invention, it is preferable to add a preservative for the purpose of preventing the growth of various bacteria during storage. Specific examples of the preservative include compounds represented by the following general formulas (I), (II), (III) and (IV). First, the compound represented by formula (I) will be described.

[0064]

[Chemical 1]

In formula (I), R ¹² and R ¹³ are each independently a hydrogen atom, an alkyl group, an aryl group, a cyano group, a heterocyclic group, an alkylthio group, an arylthio group, an alkylsulfoxy group or an alkylsulfonyl group. Represents a group.
R ¹² and R ¹³ may combine with each other to form an aromatic ring.
R ¹¹ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, a heterocyclic group or a substituent shown below.

[0066]

[Chemical 2]

In the above substituents, R ¹⁴ and R ¹⁵ each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group.

Next, the compound represented by formula (II) will be described. The general formula (II) is an embodiment in which R ¹² and R ¹³ in the general formula (I) are bonded to each other to form an aromatic ring.

[0069]

[Chemical 3]

In the general formula (II), R ²¹ , R ²² , R ²³
And R ²⁴ each independently represent a hydrogen atom, a halogen atom, or an alkyl group. R ¹¹ has the same meaning as R ¹¹ in the general formula (I).

The compounds represented by the general formulas (I) and (II) may be combined with salts such as NaCl and ammonium chloride to form sodium salts, ammonium salts and the like. less than,
Typical compounds represented by the general formulas (I) and (II) are shown, but the preservative in the present invention is not limited thereto.

[0072]

[Chemical 4]

[0073]

[Chemical 5]

Next, the compound represented by the general formula (III) will be described.

[Chemical 6]

In the general formula (III), R ¹⁶ represents a hydrogen atom or a lower alkyl group. R ^{1 7} represents a hydrogen atom, hydroxy group, lower alkyl group, or a hydroxymethyl group. Typical compounds represented by the general formula (III) are shown below, but the preservative in the present invention is not limited to these.

[0076]

[Chemical 7]

Next, the compound represented by formula (IV) will be described.

[0078]

[Chemical 8]

In the general formula (IV), R ¹⁸ , R ¹⁹ and R
²⁰ each independently represents a hydrogen atom, a lower alkyl group, a hydroxy group, a carboxylic acid or its ester, a halogen atom, a lower acyl group, an aryl group or a sulfinyl group, which may be the same or different from each other. Good. Typical compounds represented by the general formula (IV) are shown below, but the invention is not limited thereto.

[0080]

[Chemical 9]

Each of the above preservatives can be easily obtained as a commercial product. Also, among the above preservatives,
Benzisothiazolinone sodium salt is preferred.

The addition amount of the preservative is preferably 0.1 mg to 5000 mg per kg of the dispersion, and 1 mg to
1000 mg is more preferable, and 10 mg to 200 mg is further preferable.

The solid dispersion of the present invention is preferably stored or transported at a refrigerated or room temperature from the time of production to the time of use. In addition, the storage or transportation can be performed under either condition of a light room or a dark room.

[Photothermographic Material] The photothermographic material of the present invention will be described below. That is, the photothermographic material of the present invention is a photothermographic material having on a support at least one layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions and a binder. In the material, the layer and / or another layer provided on the support is
It is formed by applying and drying a coating liquid containing at least one solid dispersion of a photographically useful compound containing a dispersoid composed of an organic compound and a dispersion medium, and having the following formula: The average sedimentation velocity (v ₂₅ ) at 25 ° C. represented by (1) is 5.0 × 10 ⁻⁶ mm / sec or less. Equation ^{_{(1) v 25 = 2r 2}} g (ρs 25 -ρ 25) / 9η 25

In the above formula (1), r is the median diameter of the dispersion, g is the gravitational acceleration, ρs ₂₅ is the specific gravity of the dispersoid at 25 ° C., ρ ₂₅ is the specific gravity of the dispersion medium at 25 ° C., η ₂₅
Represents the viscosity of the dispersion at 25 ° C.

Further, the photothermographic material of the invention has at least one layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions and a binder on a support. In the photothermographic material, the layer and / or the other layer provided on the support contains at least one solid dispersion of a photographically useful compound containing a dispersoid composed of an organic compound and a dispersion medium. An average sedimentation rate (v ₁₀ ) at 25 ° C. of the dispersoid represented by the following formula (2), which is formed by applying and drying a coating solution.
Is 2.5 × 10 ⁻⁶ mm / sec or less. Equation ^{_{(2) v 10 = 2r 2}} g (ρs 10 -ρ 10) / 9η 10

In the equation (2), r is the median diameter of the dispersoid, g is the acceleration of gravity, ρs ₁₀ is the specific gravity of the dispersoid at 10 ° C., ρ ₁₀ is the specific gravity of the dispersion medium at 10 ° C., and η ₁₀
Represents the viscosity of the dispersion at 10 ° C.

In the present invention, by using the coating solution containing at least one kind of the solid dispersion of the present invention described above, a photothermographic material having an excellent coated surface state can be obtained.

The organic compound contained as a solid dispersion in the coating liquid is not particularly limited, but a reducing agent, a development accelerator, a hydrogen bonding compound, an antifoggant, a polyhalogen compound, a toning agent and the like are preferable. To be Among them,
As the solid dispersion of the present invention, a reducing agent, a development accelerator, a hydrogen bonding compound and a polyhalogen compound are preferable, and a polyhalogen compound is most preferable. Details of each compound will be described later.

The elements constituting the photothermographic material of the present invention will be described below. (Explanation of Non-Photosensitive Organic Silver Salt) The non-photosensitive organic silver salt that can be used in the present invention (hereinafter sometimes simply referred to as “organic silver salt”) is relatively stable to light. , A silver salt that forms a silver image when heated to 80 ° C. or higher in the presence of an exposed photocatalyst (such as a latent image of photosensitive silver halide) and a reducing agent. The organic silver salt may be any organic substance containing a source capable of reducing silver ions.
Regarding such a non-photosensitive organic silver salt, JP-A-10-
62899 publication, paragraphs 0048 to 0049, European Patent Publication No. 0803764A1, page 18, line 24 to page 19, line 37, European Patent Publication 096.
2812A1, JP-A-11-349591, JP-A-2000-7683, and 2000-72.
No. 711, etc.

The organic silver salt in the present invention is a silver salt of an organic acid, particularly (having 10 to 30 carbon atoms, preferably 15 to 30 carbon atoms).
Silver salts of long chain aliphatic carboxylic acids (of 28) are preferred. Preferred examples of the fatty acid silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, and silver laurate,
Examples thereof include silver caproate, silver myristate, silver palmitate, and mixtures thereof. In the present invention, among these fatty acid silver salts, it is preferable to use fatty acid silver particles having a silver behenate content of preferably 50 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more.

The shape of the organic silver salt that can be used in the present invention is not particularly limited and may be needle-like, rod-like, tabular or flaky. In the present invention, the flaky organic silver salt is used. Is preferred. Also, the ratio of the length of the long axis to the length of the single axis is 5
The following short needle-shaped, rectangular parallelepiped, cubic or potato-shaped amorphous particles are also preferably used. These organic silver particles are
It is characterized by less fog at the time of thermal development, as compared with long needle-like particles having a major axis-to-uniaxial length ratio of 5 or more.

In the present specification, the flaky organic silver salt is defined as follows. Observing the organic acid silver salt with an electron microscope, the shape of the organic acid silver salt particles is approximated to a rectangular parallelepiped,
When the sides of this rectangular parallelepiped are set to a, b, and c from the shortest side (c may be the same as b), calculation is performed using the shorter numbers a and b, and x is calculated as follows. Ask for. x = b / a

In this way, when x is obtained for about 200 particles and the average value x (average) is taken, the one satisfying the relation of x (average) ≧ 1.5 is made into flaky shape. Preferably 30 ≧ x (average) ≧ 1.5, more preferably 2
0 ≧ x (average) ≧ 2.0. By the way, needle-shaped is 1 ≦ x
(Average) <1.5.

In the scale-like particles, a can be regarded as the thickness of a tabular particle having a plane having sides b and c as a main plane. The average of a is 0.01 μm or more and 0.23 μ
m or less is preferable, and 0.1 μm or more and 0.20 μm or less is more preferable. The average of c / b is preferably 1 or more and 6 or less, more preferably 1.05 or more and 4 or less, and 1.1
It is more preferably 3 or more and 3 or less, and particularly preferably 1.1 or more and 2 or less.

The particle size distribution of the organic silver salt is preferably monodisperse. Monodisperse is the standard deviation of the lengths of the short and long axes divided by the short and long axes, which is 10
The 0 fraction is preferably 100% or less, more preferably 80%.
% Or less, more preferably 50% or less.
The shape of the organic silver salt can be measured by a transmission electron microscope image of the organic silver salt dispersion. Another method for measuring monodispersity is to calculate the standard deviation of the volume-weighted average diameter of organic silver salts. In this method, the percentage of the value divided by the volume-weighted average diameter (variation coefficient)
Is preferably 100% or less, more preferably 80% or less, still more preferably 50% or less. As a measuring method, for example, from the particle size (volume-weighted average diameter) obtained by irradiating an organic silver salt dispersed in a liquid with laser light and obtaining an autocorrelation function with respect to the time change of the fluctuation of the scattered light You can ask.

As a method for producing the organic silver salt used in the present invention and a method for dispersing the same, known methods and the like can be applied. For example, JP-A-10-62899, European Patent Publication No. 0803763A1, European Patent Publication No. 0962812A1 and JP-A No. 11-34959 described above.
No. 1, JP 2000-7683 A, 2000
-72711, Japanese Patent Application No. 11-348228-30
Japanese Patent Publication No. 11-203413, Japanese Patent Application No. 2000-
90093, 2000-195621,
2000-191226, 2000-213.
No. 813, No. 2000-214155, No. 2
Reference can be made to, for example, Japanese Patent Publication No. 000-191226.

When a photosensitive silver salt is allowed to coexist during the dispersion of the organic silver salt, fog increases and the sensitivity remarkably decreases. Therefore, it is more preferable that the photosensitive silver salt is not substantially contained during the dispersion. In the present invention, the amount of the photosensitive silver salt in the dispersed aqueous dispersion is preferably 1 mol% or less, more preferably 0.1 mol% or less, based on 1 mol of the organic silver salt in the liquid.
It is not more than mol%, and more preferable is one in which the photosensitive silver salt is not positively added.

In the present invention, a photosensitive material can be produced by mixing an organic silver salt aqueous dispersion and a photosensitive silver salt aqueous dispersion. The mixing ratio of the organic silver salt and the photosensitive silver salt can be selected according to the purpose, and the ratio of the photosensitive silver salt to the organic silver salt is preferably in the range of 1 to 30 mol%.
Is more preferably in the range of 20 to 20 mol%, particularly preferably in the range of 3 to 15 mol%. Mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions at the time of mixing is a method preferably used for controlling photographic characteristics.

[0100] In the present invention, the organic silver salt can be used in a desired amount, preferably 0.1-5 g / m ² as silver amount, more preferably 0.3 to 3 g / m ^2, 0.5 to 2 g
/ M ² is more preferable.

(Explanation of Reducing Agent) In the photothermographic material of the invention, a reducing agent for silver ions (hereinafter simply referred to as “reducing agent”)
May be referred to as)). The reducing agent for silver ions may be any substance (preferably organic substance) that reduces silver ions to metallic silver. Examples of such reducing agents include paragraphs 0043 to 0045 in JP-A No. 11-65021 and European Patent Publication No. 080.
It is described on page 7, line 34 to page 18, line 12 of JP 3764A1. As the reducing agent in the present invention, a so-called hindered phenol-based reducing agent or a bisphenol-based reducing agent having a substituent at the ortho position of the phenolic hydroxyl group is preferable, and a compound represented by the following general formula (R) is more preferable.

[0102]

[Chemical 10]

In formula (R), R ¹¹ and R ^{11 ′} each independently represent an alkyl group having 1 to 20 carbon atoms. R ¹²
And R ^{12 ′} each independently represent a hydrogen atom or a substituent capable of substituting on the benzene ring. L is an -S- group or a -CHR ¹³ -
Represents a group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. X ¹ and X ^{1 ′} each independently represent a hydrogen atom or a group capable of substituting for a benzene ring.

The general formula (R) will be described in detail. In formula (R), R ¹¹ and R ^{11 ′} each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. The substituent of the alkyl group is not particularly limited, but preferably an aryl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamide group, a sulfonyl group, a phosphoryl group, Examples thereof include an acyl group, a carbamoyl group, an ester group, a ureido group, a urethane group and a halogen atom.

R ¹¹ and R ^{11 ′} preferably have 3 to 10 carbon atoms.
15 secondary or tertiary alkyl group, specifically, isopropyl group, isobutyl group, t-butyl group, t-amyl group, t-octyl group, cyclohexyl group, cyclopentyl group, 1-methylcyclohexyl group, A 1-methylcyclopropyl group and the like can be mentioned. More preferably 4 carbon atoms
To 12 tertiary alkyl groups, among which a t-butyl group, a t-amyl group, and a 1-methylcyclohexyl group are more preferable, and a t-butyl group is the most preferable.

In formula (R), R ¹² and R ^{12 ′} each independently represent a hydrogen atom or a substituent capable of substituting on the benzene ring. R ¹² and R ^{12 ′} preferably have 1 to 2 carbon atoms.
An alkyl group of 0, specifically, methyl group, ethyl group, propyl group, butyl group, isopropyl group, t-butyl group, t-amyl group, cyclohexyl group, 1-methylcyclohexyl group, benzyl group, methoxymethyl Group, methoxyethyl group and the like. Among these, a methyl group, an ethyl group, a propyl group, an isopropyl group, and a t-butyl group are more preferable.

In the general formula (R), X ¹ and X ^{1 ′} each independently represent a hydrogen atom or a group capable of substituting for a benzene ring. The group capable of substituting on the benzene ring is preferably an alkyl group, an aryl group, a halogen atom, an alkoxy group,
Examples thereof include an acylamino group. X ¹ and X ^{1 ′} are preferably a hydrogen atom, a halogen atom or an alkyl group, more preferably a hydrogen atom.

In formula (R), L represents a --S-- group or a --CHR ¹³ --group, preferably a --CHR ¹³ --group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have a substituent. R ¹³
As specific examples of the unsubstituted alkyl group represented by, methyl group, ethyl group, propyl group, butyl group, heptyl group,
Undecyl group, isopropyl group, 1-ethylpentyl group, 2,4,4-trimethylpentyl group and the like can be mentioned.
Specific examples of the substituent of the alkyl group represented by R ¹³ include
The same groups as the substituents of R ¹¹ and R ^{11 ′} can be mentioned.

R ¹³ is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, 2,
The 4,4-trimethylpentyl group is preferred. Particularly preferable R ¹³ is a hydrogen atom, a methyl group, an ethyl group, a propyl group or an isopropyl group.

When R ¹³ is a hydrogen atom, R ¹² and R
^{12 '} is preferably an alkyl group having 2 to 5 carbon atoms,
An ethyl group and a propyl group are more preferable, and an ethyl group is most preferable. When R ¹³ is a primary or secondary alkyl group having 1 to 8 carbon atoms, R ¹² and R ^{12 ′} are preferably methyl groups. The primary or secondary alkyl group having 1 to 8 carbon atoms represented by R ¹³ is more preferably a methyl group, an ethyl group, a propyl group or an isopropyl group, further preferably a methyl group, an ethyl group or a propyl group.

When R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} are all methyl groups, R ¹³ is preferably a secondary alkyl group, such as isopropyl group, isobutyl group, 1-
The ethylpentyl group is more preferable, and the isopropyl group is particularly preferable.

The reducing agent has different heat developability, developed silver color tone and the like depending on the combination of R ¹¹ , R ^{11 '} , R ¹² , R ^12' and R ¹³ . Since these can be adjusted by combining two or more reducing agents, it is preferable to use two or more reducing agents depending on the purpose.

The specific examples (representative compounds R-1 to R-34) of the reducing agent in the invention including the compounds represented by the general formula (R) are shown below, but they can be used in the invention. The compound is not limited to these.

[0114]

[Chemical 11]

[0115]

[Chemical 12]

[0116]

[Chemical 13]

[0117]

[Chemical 14]

The amount of reducing agent added in the present invention is 0.1.
To 3.0 g / m ² , more preferably 0.2 to 1.5 g / m ² , and even more preferably 0.3.
Is about 1.0 g / m ² . Silver on the side with the image forming layer 1
The amount is preferably 5 to 50% by mol, more preferably 8 to 30% by mol, and 10 to 20% by mol.
More preferably, it is contained in mol%. The reducing agent is preferably contained in the image forming layer.

The reducing agent may be contained in the coating liquid by any method such as a solution form, an emulsified dispersion form and a solid dispersion form, but it is preferably contained as the solid dispersion of the present invention.

As a well-known emulsification dispersion method, oils such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, and an auxiliary solvent such as ethyl acetate or cyclohexanone are dissolved and mechanically emulsified. The method of producing a dispersion is mentioned.

As the solid fine particle dispersion method, the powder of the reducing agent is dispersed in a suitable solvent such as water by a ball mill, a colloid mill, a vibrating ball mill, a sand mill, a jet mill, a roller mill or ultrasonic waves to obtain a solid dispersion. The method of producing a thing is mentioned. At that time, a protective colloid (for example, polyvinyl alcohol) or a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions) or the like) may be used. Good.
In the above mills, beads such as zirconia are usually used as a dispersion medium, and Zr or the like eluted from these beads may be mixed in the dispersion. Normally, the range of 1 ppm to 1000 ppm is preferable, although it depends on the dispersion conditions. Zr content in the photosensitive material is 0.5 m per 1 g of silver
If it is g or less, there is no problem in practical use. The water dispersion preferably contains a preservative (for example, benzoisothiazolinone sodium salt).

(Explanation of Development Accelerator) The photothermographic material of the invention preferably contains a development accelerator. As the development accelerator, the general formula (A) described in JP-A-2000-267222, JP-A-2000-330234 and the like can be used.
And a hindered phenolic compound represented by the general formula (II) described in JP-A No. 2001-92075, JP-A No. 10-
A hydrazine compound represented by the general formula (I) described in JP-A-62895 or JP-A-11-15116 or the general formula (1) described in Japanese Patent Application No. 2001-074278, Japanese Patent Application No. 2000-2000. A phenol-based or naphthol-based compound represented by the general formula (2) described in the specification of -76240 is preferably used. The amount of these development accelerators added is 0.1 to 20 mol% with respect to the reducing agent.
Is preferable, the range of 0.5 to 10 mol% is more preferable, and the range of 1 to 5 mol% is further preferable.

The method for introducing the photothermographic material may be the same as that for the reducing agent, but it is particularly preferable to add it as a solid dispersion or an emulsion dispersion, more preferably as a solid dispersion. preferable. When added as a solid dispersion, the solid dispersion is preferably the solid dispersion of the present invention. When added as an emulsified dispersion, it is added as an emulsified dispersion dispersed using a high boiling solvent and a low boiling auxiliary solvent that are solid at room temperature, or a so-called oilless emulsion dispersion that does not use a high boiling solvent. It is preferable to add it as a substance.

(Explanation of Hydrogen Bonding Compound) The photothermographic material of the invention preferably contains a hydrogen bonding compound. The reducing agent in the present invention is an aromatic hydroxyl group (—O
H), particularly in the case of the above-mentioned bisphenols, it is preferable to use a non-reducing compound having a group capable of forming a hydrogen bond with these groups in combination. Examples of the group forming a hydrogen bond with a hydroxyl group or an amino group include a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. Can be mentioned. Of these, preferred are phosphoryl groups, sulfoxide groups, and amide groups (provided that> N—H groups are not included,> N—R
a (wherein Ra is a substituent other than H), a urethane group [provided that it has no> NH group, and> N-
Such as Ra (Ra is a substituent other than H), a ureido group (provided that it has no> N—H group, and> N—
Ra (wherein Ra is a substituent other than H) is blocked].

Particularly preferred hydrogen-bonding compounds in the present invention include compounds represented by the following general formula (D).

[0126]

[Chemical 15]

In the general formula (D), R ²¹ , R ²² and R
Each ²³ independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group, and these groups may be unsubstituted or may have a substituent.

When R ²¹ , R ²² and R ²³ have a substituent, the substituent is a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, Examples thereof include a sulfonamide group, an acyloxy group, an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, and a phosphoryl group, preferably an alkyl group or an aryl group, and specific examples include a methyl group, an ethyl group, and an isopropyl group. , T-butyl group, t-octyl group, phenyl group, 4-alkoxyphenyl group, 4-acyloxyphenyl group and the like.

Examples of the alkyl group represented by R ²¹ , R ²² and R ²³ include a methyl group, an ethyl group, a butyl group, an octyl group, a dodecyl group, an isopropyl group, a t-butyl group and a t-group.
Amyl group, t-octyl group, cyclohexyl group, 1-methylcyclohexyl group, benzyl group, phenethyl group, 2
-Phenoxypropyl group and the like.

Examples of the aryl group represented by R ²¹ , R ²² and R ²³ include phenyl group, cresyl group, xylyl group, naphthyl group, 4-t-butylphenyl group, 4-t-octylphenyl group and 4- Examples thereof include anisidyl group and 3,5-dichlorophenyl group.

Examples of the alkoxy group represented by R ²¹ , R ²² and R ²³ include methoxy group, ethoxy group, butoxy group, octyloxy group, 2-ethylhexyloxy group, 3,
A 5,5-trimethylhexyloxy group, a dodecyloxy group, a cyclohexyloxy group, a 4-methylcyclohexyloxy group, a benzyloxy group and the like can be mentioned.

Examples of the aryloxy group represented by R ²¹ , R ²² and R ²³ include a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-t-butylphenoxy group, a naphthoxy group and a biphenyloxy group.

The amino groups represented by R ²¹ , R ²² and R ²³ include dimethylamino group, diethylamino group, dibutylamino group, dioctylamino group, N-methyl-N-hexylamino group, dicyclohexylamino group and diphenyl. Examples thereof include an amino group and an N-methyl-N-phenylamino group.

The heterocyclic group represented by R ²¹ , R ²² and R ²³ includes an imidazole ring group, a pyridine ring group, a pyrrole ring group, a thiophene ring group, a thiazole ring group, an oxazole ring group, a pyran ring group and a pyrazoline. Ring group, piperidine ring group,
Examples thereof include piperazine ring group, morpholine ring group, indole ring group, quinoline ring group and the like.

As R ²¹ , R ²² and R ²³ , an alkyl group, an aryl group, an alkoxy group and an aryloxy group are preferable. From the viewpoint of the effect of the present invention, at least one or more of R ²¹ , R ²² and R ²³ is preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. In addition, R ²¹ , R ²² and R ²³ are preferably the same group in that they can be obtained at low cost.

Specific examples of the hydrogen-bonding compounds including the compounds represented by the general formula (D) (exemplified compound D) are shown below.
-1 to D-21) are shown, but the compounds that can be used in the present invention are not limited to these.

[0137]

[Chemical 16]

[0138]

[Chemical 17]

[0139]

[Chemical 18]

Specific examples of the hydrogen-bonding compound include, in addition to those described above, European Patent No. 1096310 and Japanese Patent Application No. 2000.
-270498 specification and the thing of 2001-124796 specification are mentioned. The hydrogen-bonding compound in the present invention can be contained in the coating liquid in the form of a solution, an emulsified dispersion, or a solid dispersion, like the reducing agent. When added as a solid dispersion, the solid dispersion is preferably the solid dispersion of the present invention.

The compound of the present invention forms a hydrogen-bonding complex with a compound having a phenolic hydroxyl group or an amino group in a solution state, and is a combination of a reducing agent and a compound represented by the general formula (D). In some cases, it can be isolated as a complex in a crystalline state. It is particularly preferable to use the crystal powder thus isolated as a solid fine particle dispersion in order to obtain stable performance. Further, a method in which a reducing agent and the compound represented by the general formula (D) are mixed in powder form and a complex is formed at the time of dispersion with a sand grinder mill or the like using an appropriate dispersant can also be preferably used. The addition amount of the hydrogen-bonding compound represented by the general formula (D) in the present invention is preferably 1 to 200 mol%, more preferably 10 to 150 mol%, and more preferably 20 to the reducing agent. The range of up to 100 mol% is more preferred.

(Explanation of Photosensitive Silver Halide) The photosensitive silver halide used in the present invention (hereinafter sometimes simply referred to as “silver halide”) is not particularly limited in halogen composition, and silver chloride, Silver chlorobromide, silver bromide, silver iodobromide,
Silver iodochlorobromide and silver iodide can be used. Among them, silver bromide and silver iodobromide are preferable. The distribution of the halogen composition in the grain may be uniform, the halogen composition may be changed stepwise, or the halogen composition may be continuously changed. Further, silver halide grains having a core / shell structure can be preferably used.
A preferred structure is a 2- to 5-fold structure, and more preferably a 2- to 4-fold structure core / shell particles can be used. Further, a technique of localizing silver bromide or silver iodide on the surface of silver chloride, silver bromide or silver chlorobromide grains can also be preferably used.

Methods of forming photosensitive silver halide are well known in the art and are described, for example, in Research Disclosure, June 1978, No. 17029, and US Pat. No. 3,700,458. Can be used. Specifically, a photosensitive silver halide is prepared by adding a silver-providing compound and a halogen-providing compound to gelatin or another polymer solution,
After that, a method of mixing with an organic silver salt is used. In addition, paragraph numbers 0217 to 02 of JP-A No. 11-119374.
24, the methods described in Japanese Patent Application Nos. 11-98708 and 2000-347335 are also preferable.

The particle size of the photosensitive silver halide is preferably small for the purpose of suppressing white turbidity after image formation, specifically 0.20 μm or less, more preferably 0.01 μm or more and 0.15 μm or less. , And more preferably 0.02 μm or more and 0.12 μm or less. The grain size as used herein refers to the diameter when converted into a circular image having the same area as the projected area of silver halide grains (projected area of the principal plane in the case of tabular grains).

Examples of the shape of the photosensitive silver halide grains include cubes, octahedra, tabular grains, spherical grains, rod-shaped grains and potato-shaped grains, but in the present invention, cubic grains are particularly preferable. Grains with rounded corners of silver halide grains can also be preferably used. The surface index (Miller index) of the outer surface of the photosensitive silver halide grain is not particularly limited, but the {100} plane, which has high spectral sensitization efficiency when a spectral sensitizing dye is adsorbed, may be high. preferable. The ratio is preferably 50% or more, more preferably 65% or more, still more preferably 80% or more. The ratio of the {100} planes of the Miller index is measured by T.M. Tani; J. Imagin
g Sci. , 29, 165 (1985).

In the present invention, the hexacyano metal complex is granulated.
A silver halide grain present on the outermost surface of the child is preferable. Six
Examples of cyano metal complexes include [Fe (CN)₆]^Four-, [F
e (CN)₆]^3-, [Ru (CN)₆]^Four-, [Os (C
N)₆]^Four-, [Co (CN)₆] ^3-, [Rh (CN)₆]
^3-, [Ir (CN)₆]^3-, [Cr (CN)₆]^3-, [R
e (CN)₆]^3-Etc. In the present invention,
A cyano Fe complex is preferred.

Since the hexacyano metal complex exists in the form of an ion in an aqueous solution, the counter cation is not important, but it is easily miscible with water and is suitable for the precipitation operation of a silver halide emulsion. Ion, rubidium ion, cesium ion, alkali metal ion such as lithium ion, ammonium ion, alkylammonium ion (eg, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetra (n-butyl) ammonium ion) is used. It is preferable.

The hexacyano metal complex is a mixed solvent with water or a suitable organic solvent miscible with water (for example, alcohols, ethers, glycols, ketones, esters, amides, etc.) and gelatin. It can be mixed with and added.

The addition amount of the hexacyano metal complex is preferably 1 × 10 ⁻⁵ mol or more and 1 × 10 ⁻² mol or less, and more preferably 1 × 10 ⁻⁴ mol or more and 1 × 10 ⁻³ mol or less per mol of silver. Is.

In order to allow the hexacyano metal complex to exist on the outermost surface of the silver halide grain, after the addition of the hexacyano metal complex to the silver nitrate aqueous solution used for grain formation is completed, sulfur sensitization, selenium sensitization and tellurium sensitization are carried out. Of the chalcogen sensitization or gold sensitization before the chemical sensitization step before the chemical sensitization step, before the washing step, during the dispersion step, or directly before the chemical sensitization step. In order to prevent silver halide fine grains from growing, it is preferable to add the hexacyano metal complex immediately after the grain formation, and preferably before the end of the charging step.

The addition of the hexacyano metal complex may be started after adding 96% by mass of the total amount of silver nitrate to be added for grain formation, or after adding 98% by mass. More preferably, and particularly preferably after addition of 99% by mass.

When these hexacyano metal complexes are added after the aqueous silver nitrate solution just before the completion of grain formation, they can be adsorbed on the outermost surface of the silver halide grain, and most of them are hardly soluble with silver ions on the grain surface. Form a salt. Since this silver salt of hexacyanoiron (II) is less soluble than AgI, redissolution by fine particles can be prevented, and fine silver halide grains having a small grain size can be produced.

The photosensitive silver halide grain of the present invention can contain a metal or a metal complex of Group 8 to Group 10 of the Periodic Table (showing Groups 1 to 18). Rhodium, ruthenium, and iridium are preferable as the metal of Group 8 to 10 of the periodic table or the central metal of the metal complex. One of these metal complexes may be used, or two or more of the same metal complex and different metal complexes may be used in combination. The content is preferably 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol per mol of silver. Regarding these heavy metals and metal complexes and addition methods thereof, JP-A-7-225449,
Paragraph numbers 0018 to 0 of JP-A No. 11-65021
No. 024, paragraph number 0 of JP-A No. 11-119374.
227-0240.

Furthermore, the metal atom (eg, [Fe) which can be contained in the silver halide grains used in the present invention.
(CN) ₆ ] ^4- ), for the desalting method and the chemical sensitizing method of the silver halide emulsion, paragraph Nos. 0046 to 0050 of JP-A No. 11-84574 and paragraph No. 0025 of JP-A No. 11-65021. To 0031, JP-A-11-119
It is described in paragraph Nos. 0242 to 0250 of Japanese Patent No. 374.

As the gelatin contained in the photosensitive silver halide emulsion used in the present invention, various gelatins can be used. In order to maintain a good dispersion state of the photosensitive silver halide emulsion in a coating solution containing an organic silver salt, it is preferable to use low molecular weight gelatin having a molecular weight of 500 to 60,000. These low molecular weight gelatins may be used during grain formation or dispersion after desalting treatment, but are preferably used during dispersion after desalting treatment.

The sensitizing dye applicable to the photosensitive silver halide in the present invention is a sensitizing dye capable of spectrally sensitizing silver halide grains in a desired wavelength region when adsorbed on silver halide grains. A sensitizing dye having a spectral sensitivity suitable for the characteristics can be advantageously selected. Regarding the sensitizing dye and the addition method, JP-A No. 11-65021, paragraph numbers 0103 to 0109 and JP-A No. 10-18657.
The compound represented by the general formula (II) in JP-A No.
No. 119374, a dye represented by the general formula (I) and paragraph No. 0106, U.S. Pat. Nos. 5,510,236 and 3,871,887, and the dye described in Example 5; JP-A-2-96131 and JP-A-59-4
Dyes disclosed in Japanese Patent No. 8753, European Patent Publication No. 0803764A1, page 19, line 38 to page 20, line 35, Japanese Patent Application No. 2000-86865, Japanese Patent Application No. 2000-102560, Japanese Patent Application 200
0-205399 specification etc. are described. These sensitizing dyes may be used alone or in combination of two or more kinds. In the present invention, the sensitizing dye is added to the silver halide emulsion preferably after the desalting step and before coating, more preferably after the desalting step and before the start of chemical ripening. The addition amount of the sensitizing dye in the present invention can be a desired amount depending on the sensitivity and fog performance, but it is 10 per 1 mol of silver halide in the photosensitive layer.
^-6 to 1 mol is preferable, and 10 ^-4 to 10 is more preferable.
^-1 mol.

In the present invention, a supersensitizer can be used in order to improve the spectral sensitization efficiency. Examples of the supersensitizer that can be used in the present invention include European Patent Publication No. 587,338 and US Pat. No. 3,877,94.
No. 3, No. 4,873,184, No. 5-341432, No. 11-109547, No. 10-111543, and the like.

The photosensitive silver halide grains in the present invention are preferably chemically sensitized by a sulfur sensitizing method, a selenium sensitizing method or a tellurium sensitizing method. Known compounds are preferably used in the sulfur sensitization method, the selenium sensitization method, and the tellurium sensitization method, for example, JP-A-7-12876.
The compounds described in JP-A-8, etc. can be used.
Particularly in the present invention, tellurium sensitization is preferable, and JP
Compounds described in the literature described in paragraph No. 0030 of JP-A 1-65021 and compounds represented by formulas (II), (III) and (IV) in JP-A-5-313284 are more preferable.

The chemical sensitization in the present invention can be carried out at any time after grain formation and before coating.
There may be (1) before spectral sensitization, (2) simultaneously with spectral sensitization, (3) after spectral sensitization, (4) immediately before coating, and the like. In particular, it is preferably performed after spectral sensitization. The amount of the sulfur, selenium and tellurium sensitizers used in the present invention varies depending on the silver halide grains used, chemical ripening conditions and the like, but is 10 ^-8 to 10 ^-2 mol, preferably 1 ^-8 mol, per mol of silver halide. About 10 ⁻⁷ to 10 ⁻³ mol is used. The conditions of the chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, and the temperature is 40 to.
It is about 95 ° C. A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method disclosed in EP-A-293,917.

The photosensitive silver halide emulsion in the photothermographic material of the present invention may be of one kind or of two or more kinds (for example, those having different average grain sizes, those having different halogen compositions, those having different crystal habits). , Different chemical sensitization conditions) may be used together. Gradation can be adjusted by using a plurality of photosensitive silver halides having different sensitivities. Techniques relating to these are disclosed in JP-A-57-119341, JP-A-53-106125, and JP-A-47-3929.
No. 48, 55730 and No. 46-5187.
No. 50-73627, No. 57-1508.
No. 41 publication and the like are listed. As a difference in sensitivity, it is preferable that each emulsion has a difference of 0.2 log E or more.

The amount of photosensitive silver halide added is 0.03 to 0.6 g, which is the amount of coated silver per 1 m ² of the light-sensitive material.
Is preferably / m ^2, 0.07~0.4g / m ²
Is more preferable, and 0.05 to 0.3 g / m
Most preferably, it is ² . The photosensitive silver halide is preferably 0.01 mol or more and 0.5 mol or less, and more preferably 0.02 mol or more and 0.1 mol or less with respect to 1 mol of the organic silver salt.
3 mol or less, more preferably 0.03 mol or more and 0.2
It is less than or equal to mol.

Regarding the mixing method and mixing conditions of the separately prepared photosensitive silver halide and organic silver salt, the prepared silver halide grains and organic silver salt are respectively mixed with a high-speed stirrer, a ball mill, a sand mill, a colloid mill, and a vibration. There is a method of mixing with a mill, a homogenizer or the like, or a method of preparing an organic silver salt by mixing photosensitive silver halide prepared at any timing during preparation of the organic silver salt. There is no particular limitation as long as the effect is sufficiently exhibited. In addition, mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions at the time of mixing is a preferable method for controlling photographic characteristics.

The silver halide of the present invention is preferably added to the coating solution for the image forming layer 180 minutes before to immediately before coating, preferably 60 minutes to 10 seconds before coating. The mixing method and the mixing conditions are as follows. Is not particularly limited as long as the effects of the present invention are sufficiently exhibited. Specific mixing methods include a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is set to a desired time, or N.I. Harnby, M .; F. Edward
s, A.S. W. There is a method using a static mixer described in Chapter 8 of Nienow's "Liquid Mixing Technology" translated by Koji Takahashi (published by Nikkan Kogyo Shimbun, 1989).

(Description of Binder) As the binder of the organic silver salt-containing layer (that is, the image forming layer) of the present invention, any polymer may be used. Suitable binders are transparent or translucent, generally colorless, natural resins, polymers and copolymers, synthetic resins and polymers and copolymers, and other film-forming media such as gelatins, gums, poly (vinyl alcohol). ), Hydroxyethyl celluloses, cellulose acetates,
Cellulose acetate butyrate, poly (vinylpyrrolidone) s, casein, starch, poly (acrylic acid)
, Poly (methylmethacrylic acid) s, poly (vinyl chloride) s, poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, Poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters),
Poly (urethane) s, phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates), poly (vinyl acetate) s, poly (olefins)
, Cellulose esters, poly (amide) s and the like. The binder may be formed by coating with water, an organic solvent or an emulsion.

In the present invention, the glass transition temperature of the binder that can be used in combination with the layer containing the organic silver salt is 10 ° C. or higher 8
It is preferably 0 ° C. or lower (hereinafter sometimes referred to as high Tg binder), more preferably 15 ° C. to 70 ° C., and further preferably 20 ° C. or higher and 65 ° C. or lower.

In this specification, Tg was calculated by the following formula. 1 / Tg = Σ (Xi / Tgi) Here, it is assumed that the polymer is a copolymer of n monomer components from i = 1 to n. Xi is the weight fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer.
However, Σ is the sum of i = 1 to n. The homopolymer glass transition temperature value (Tgi) of each monomer is P
polymer Handbook (3rd Editi
on) (J. Brandrup, EH Immer.
gut (Wiley-Interscience, 1
989)) was adopted.

Two or more binders may be used in combination, if desired. Further, those having a glass transition temperature of 20 ° C. or higher and those having a glass transition temperature of less than 20 ° C. may be used in combination. When two or more polymers having different Tgs are blended and used, the weight average Tg is preferably within the above range.

In the present invention, it is preferable that the organic silver salt-containing layer is coated with a coating solution (water-based coating solution) in which 30% by mass or more of the solvent is water and dried to form a coating film.
In the present invention, the organic silver salt-containing layer contains 30% by mass of the solvent.
When the above is formed by coating using a coating liquid that is water and drying, and when the binder of the organic silver salt-containing layer is soluble or dispersible in an aqueous solvent (aqueous solvent), especially 25 Performance is improved when the polymer latex has an equilibrium water content of 2% by mass or less at a temperature of 60% RH. The most preferable form is prepared so that the ionic conductivity is 2.5 mS / cm or less, and such a preparation method includes a method of purifying using a separation functional membrane after polymer synthesis.

The aqueous solvent in which the polymer is soluble or dispersible as used herein is water or a mixture of water and 70% by mass or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include alcohols such as methanol, ethanol and propyl alcohol, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, ethyl acetate, dimethylformamide and the like.

The term "aqueous solvent" is also used herein in the case of a system in which the polymer is not thermodynamically dissolved and exists in a so-called dispersed state.

"Equilibrium water content at 25 ° C. 60% RH" means the weight W1 of the polymer in the humidity controlled equilibrium under the atmosphere of 25 ° C. 60% RH and the weight W0 of the polymer in the absolutely dry state at 25 ° C. It can be expressed as follows. Equilibrium water content at 25 ° C. and 60% RH = {(W1-W
0) / W0} × 100 (mass%)

The definition and measurement method of the water content can be referred to, for example, Polymer Engineering Course 14, Polymer Material Testing Method (edited by The Polymer Society of Japan, Jijijinkan).

25 ° C. of the binder polymer of the present invention 60 ° C.
The equilibrium water content in% RH is preferably 2% by mass or less, more preferably 0.01% by mass or more and 1.
5 mass% or less, more preferably 0.02 mass% or more 1
Mass% or less is desirable.

In the present invention, a polymer dispersible in an aqueous solvent is particularly preferable. Examples of the dispersed state may be a latex in which fine particles of a water-insoluble hydrophobic polymer are dispersed, or those in which polymer molecules are dispersed in a molecular state or forming micelles, but latex dispersed particles are more preferable. preferable. The average particle size of the dispersed particles is 1 to 500.
The range is 00 nm, preferably 5 to 1000 nm, more preferably 10 to 500 nm, still more preferably 50 to 200 nm. The particle size distribution of the dispersed particles is not particularly limited, and may be a wide particle size distribution or a monodisperse particle size distribution. Mixing and using two or more kinds having a monodisperse particle size distribution is also a preferable use method for controlling the physical properties of the coating solution.

In the present invention, preferred examples of the polymer dispersible in an aqueous solvent include acrylic polymers, poly (esters), rubbers (for example, SBR resin), poly (urethane) s, poly (vinyl chloride) s, Hydrophobic polymers such as poly (vinyl acetate) s, poly (vinylidene chloride) s, and poly (olefins) can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more kinds of monomers. The copolymer may be a random copolymer or a block copolymer. The number average molecular weight of these polymers is 5,000 to 1,000,000, preferably 10,000 to 200,000. If the molecular weight is too small, the mechanical strength of the emulsion layer is insufficient, and if it is too large, the film formability is poor and it is not preferred. A crosslinkable polymer latex is particularly preferably used.

-Specific Examples of Latex- Specific examples of the polymer latex in the present invention include:
The following can be mentioned. In the following, the raw material monomers are used, and the numerical values in parentheses are mass% and the molecular weights are number average molecular weights. When a polyfunctional monomer is used, the concept of molecular weight cannot be applied because a crosslinked structure is formed, so the term "crosslinkable" is used and the description of molecular weight is omitted. Tg represents a glass transition temperature.

P-1; -MMA (70) -EA (27) -MAA (3) -latex (molecular weight 37,000, Tg 61 ° C.) P-2; -MMA (70) -2EHA (20) -St (5 ) -AA (5) -latex (Mw 40,000, Tg59 ℃) P-3; -St (50) -Bu (47) -MAA (3) -latex (crosslinkable, Tg-
17 ℃) P-4; -St (68) -Bu (29) -AA (3) -latex (crosslinkable, Tg17
℃) P-5; -St (71) -Bu (26) -AA (3)-latex (crosslinkable, Tg24
℃) P-6; -St (70) -Bu (27) -IA (3) -latex (crosslinkable) P-7; -St (75) -Bu (24) -AA (1) -latex (Crosslinkability, Tg29
℃) P-8; -St (60) -Bu (35) -DVB (3) -MAA (2) -latex (crosslinkable) P-9; -St (70) -Bu (25) -DVB ( 2) -AA (3) -latex (crosslinkable) P-10; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5) -latex (molecular weight 80,000) P-11; -VDC (85) -MMA (5) -EA (5) -MAA (5) -latex (molecular weight 67000) P-12; -Et (90) -MAA (10) -latex (molecular weight 12000) P-13; -St (70) -2EHA (27) -AA (3) latex (molecular weight 130
000, Tg43 ℃) P-14; -MMA (63) -EA (35) -AA (2) latex (molecular weight 330
00, Tg47 ℃) P-15; -St (70.5) -Bu (26.5) -AA (3) -latex (crosslinking,
Tg23 ℃) P-16; -St (69.5) -Bu (27.5) -AA (3) -latex (crosslinkable,
(Tg20.5 ° C)

The abbreviations for the above structures represent the following monomers:
MMA; methyl methacrylate, EA; ethyl acrylate, MAA; methacrylic acid, 2EHA; 2-ethylhexyl acrylate, St; styrene, Bu; butadiene, AA; acrylic acid, DVB; divinylbenzene,
VC; vinyl chloride, AN; acrylonitrile, VDC;
Vinylidene chloride, Et; ethylene, IA; itaconic acid.

The polymer latexes described above are commercially available, and the following polymers can be used. Examples of acrylic polymers include Sebian A-463
5,4718,4601 (above, manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 82
Examples of poly (ester) s such as 1,820,857 (manufactured by Nippon Zeon Co., Ltd.) include FINETEX.
ES (650, 611, 675, 850 (manufactured by Dainippon Ink and Chemicals, Inc.), WD-size, WMS (manufactured by Eastman Chemical), poly (urethane)
Examples of classes include HYDRAN AP10, 20, 3
Examples of rubbers such as 0, 40 (all manufactured by Dainippon Ink and Chemicals, Inc.) include LACSTAR 7310K, 33.
07B, 4700H, 7132C (all manufactured by Dainippon Ink and Chemicals, Inc.), Nipol Lx416, 410, 4
38C, 2507 (above, manufactured by Nippon Zeon Co., Ltd.),
Examples of poly (vinyl chloride) s include G351 and G57.
Examples of poly (vinylidene chloride) such as 6 (above, manufactured by Nippon Zeon Co., Ltd.) include L502, L513 (above,
Examples of poly (olefin) s such as Asahi Kasei Co., Ltd. include Chemipearl S120 and SA100 (above, manufactured by Mitsui Petrochemical Co., Ltd.).

These polymer latices may be used alone, or may be used by blending two or more kinds as required.

-Preferable Latex- As the polymer latex used in the present invention, a latex of a styrene-butadiene copolymer is particularly preferable. The weight ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably 40:60 to 95: 5. Also,
The proportion of the styrene monomer unit and the butadiene monomer unit in the copolymer is preferably 60 to 99 mass%. The polymer latex of the present invention preferably contains acrylic acid or methacrylic acid in an amount of 1 to 6% by mass, and more preferably 2 to 5% by mass, based on the sum of styrene and butadiene. The polymer latex of the present invention preferably contains acrylic acid.

Styrene which is preferably used in the present invention
As the latex of the butadiene acid copolymer, the above-mentioned P
-3 to P-8,15, commercially available LACSTAR-3
307B, 7132C, Nipol Lx416 and the like.

The organic silver salt-containing layer of the light-sensitive material of the present invention comprises
If necessary, hydrophilic polymers such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose and carboxymethyl cellulose may be added. The amount of these hydrophilic polymers added is preferably 30% by mass or less, and more preferably 20% by mass or less, based on the total binder of the organic silver salt-containing layer.

The organic silver salt-containing layer (that is, the image forming layer) of the present invention is preferably formed using a polymer latex. The amount of the binder in the organic silver salt-containing layer is preferably such that the total binder / organic silver salt mass ratio is 1/10 to 10/1, more preferably 1/3 to 5/1, and 1/1 The range of 3/1 is more preferable.

Further, such an organic silver salt-containing layer is usually also a photosensitive layer (emulsion layer) containing a photosensitive silver halide which is a photosensitive silver salt, and in such a case, all binders are contained. The mass ratio of / silver halide is preferably in the range of 400 to 5, more preferably in the range of 200 to 10.

The total amount of binder in the image forming layer of the present invention is preferably in the range of 0.2 to 30 g / m ² , preferably 1 to
More preferably in the range of 15 g / m ^2, more preferably in the range of 2 to 10 g / m ^2. A cross-linking agent for cross-linking, a surfactant for improving coatability, and the like may be added to the image forming layer of the present invention.

(Preferable Solvent for Coating Liquid) The solvent for the coating liquid for the organic silver salt-containing layer of the light-sensitive material of the present invention (herein, the solvent and the dispersion medium are collectively referred to as solvent) is 30% by mass of water. An aqueous solvent containing the above is preferable. As a component other than water, any water-miscible organic solvent such as methanol, ethanol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, or ethyl acetate may be used. Water content of solvent of coating liquid is 50% by mass
As described above, more preferably 70% by mass or more. As an example of a preferable solvent composition, in addition to water, water / methanol = 90/10, water / methanol = 70/30, water / methanol / dimethylformamide = 80/15/5, water /
Methanol / ethyl cellosolve = 85/10/5, water /
Methanol / isopropyl alcohol = 85/10/5
Etc. (numerical value is% by mass).

(Explanation of Antifoggant, etc.) Antifoggants, stabilizers and stabilizer precursors which can be used in the present invention are disclosed in paragraph No. 00 of JP-A No. 10-62899.
70, those disclosed in European Patent Publication No. 0803764A1, page 20, line 57 to page 21, line 7, compounds described in JP-A-9-281637 and 9-329864, US Pat. , 083,681, 6,083,681, European Patent 1048975.
And the compounds described in the specification. The antifoggants preferably used in the present invention are organic halides, and examples thereof include those disclosed in paragraph Nos. 0111 to 0112 of JP-A No. 11-65021. Particularly, an organic halogen compound represented by the formula (P) in JP-A-2000-284399, JP-A-1
The organic polyhalogen compounds represented by the general formula (II) in JP-A No. 0-339934 and the organic polyhalogen compounds described in JP 2001-31644 A and JP 2001-33911 A are preferable.

-Explanation of Polyhalogen Compound- The preferred polyhalogen compound used in the present invention will be specifically described below. The preferred polyhalogen compound in the present invention is an organic polyhalogen compound represented by the following general formula (H). Formula (H) Q- (Y) n -C (Z 1) (Z 2) X

In the general formula (H), Q is an alkyl group,
It represents an aryl group or a heterocyclic group, Y represents a divalent linking group, n represents 0 or 1, Z ₁ and Z ₂ represent a halogen atom, and X represents a hydrogen atom or an electron-withdrawing group.

In the general formula (H), Q preferably represents a phenyl group substituted with an electron-withdrawing group whose Hammett's substituent constant σp has a positive value. Regarding the Hammett's substituent constant, Journal of Medicinal
Chemistry, 1973, Vol. 16, N
o. 11, 1207-1216 can be referred to. Examples of such an electron-withdrawing group include a halogen atom (fluorine atom (σp value: 0.06), chlorine atom (σp value: 0.23), bromine atom (σp value: 0.2).
3), iodine atom (σp value: 0.18)), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl (σp value: 0.33), trifluoromethyl (σp value: 0) .54)), a cyano group (σp value: 0.6)
6), nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group (for example, methanesulfonyl (σp value: 0.72)), aliphatic / aryl or heterocyclic acyl group (for example, Acetyl (σp value: 0.5
0), benzoyl (σp value: 0.43)), alkynyl group (for example, C≡CH (σp value: 0.23)), aliphatic / aryl or heterocyclic oxycarbonyl group (for example, methoxycarbonyl (σp value). : 0.45), phenoxycarbonyl (σp value: 0.44)), carbamoyl group (σp value: 0.36), sulfamoyl group (σp value:
0.57), a sulfoxide group, a heterocyclic group, a phosphoryl group and the like. The σp value is preferably 0.2 to
It is in the range of 2.0, and more preferably in the range of 0.4 to 1.0. Particularly preferable as the electron-withdrawing group are a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group and an alkylphosphoryl group, and among them, a carbamoyl group is the most preferable.

In the general formula (H), X is preferably an electron-withdrawing group, more preferably a halogen atom, an aliphatic aryl or heterocyclic sulfonyl group, an aliphatic
An aryl or heterocyclic acyl group, an aliphatic aryl or heterocyclic oxycarbonyl group, a carbamoyl group, and a sulfamoyl group are preferable, and a halogen atom is particularly preferable. Among the halogen atoms, preferably a chlorine atom, a bromine atom, an iodine atom, more preferably a chlorine atom,
A bromine atom, particularly preferably a bromine atom.

[0193] In formula (H), Y is preferably -C (= O) -, - SO- or -SO ₂ -; more preferably, -C (= O) -, - SO 2 - in There, particularly preferably -SO ₂ - is. n represents 0 or 1, and is preferably 1.

Specific examples of the compounds represented by formula (H) (exemplified compounds H-1 to H-24) are shown below, but the compounds usable in the present invention are not limited thereto. Absent.

[0195]

[Chemical 19]

[0196]

[Chemical 20]

The addition amount of the polyhalogen compound represented by the general formula (H) in the present invention is preferably in the range of 10 ⁻⁴ to 1 mol, more preferably 1 mol per 1 mol of the non-photosensitive silver salt in the image forming layer. The range of 10 ^{−3 to} 0.5 mol is more preferable, and the range of 1 × 10 ^{−2 to} 0.2 mol is further preferable.

In the present invention, the method of incorporating the antifoggant into the light-sensitive material may be the method described in the method for incorporating the reducing agent, and the organic polyhalogen compound is preferably added in the form of a solid dispersion. More preferably, the solid dispersion is the solid dispersion of the present invention.

-Other antifoggants-For other antifoggants, JP-A-11-65021 is used.
Mercury (II) salt in paragraph No. 0113, Paragraph No. 01 of the same paragraph
14 benzoic acids, salicylic acid derivative of JP-A-2000-206642, formalin scavenger compound represented by formula (S) of JP-A-2000-221634, triazine compound according to claim 9 of JP-A-11-352624, 4-hydroxy-6-methyl-1,3, a compound represented by the general formula (III) of Kaihei 6-11791
3a, 7-tetrazaindene and the like.

The photothermographic material in the invention may contain an azolium salt for the purpose of preventing fog. As the azolium salt, compounds represented by formula (XI) described in JP-A-59-193447, JP-B-55-12
Compounds described in Japanese Patent No. 581, JP-A-60-153039
Examples thereof include compounds represented by the general formula (II) described in JP-A No. The azolium salt may be added to any part of the light-sensitive material, but the addition layer is preferably added to the layer on the side having the photosensitive layer, more preferably to the organic silver salt-containing layer. The azolium salt may be added at any step in the preparation of the coating solution, and when it is added to the organic silver salt-containing layer, it may be at any step from the preparation of the organic silver salt to the preparation of the coating solution, but after the preparation of the organic silver salt. Therefore, immediately before coating is preferable. The addition method of azolium salt is powder, solution,
Any method such as fine particle dispersion may be used. Also,
You may add as a solution mixed with other additives, such as a sensitizing dye, a reducing agent, and a toning agent. In the present invention, the amount of the azolium salt added may be any amount, but it is preferably 1 × 10 ⁻⁶ mol or more and 2 mol or less, preferably 1 × 10 ⁶ mol / mol silver.
^It is more preferably ^-3 mol or more and 0.5 mol or less.

In the present invention, a mercapto compound, a disulfide compound or a thione compound is contained for the purpose of suppressing or accelerating the development to control the development, improving the spectral sensitization efficiency, and improving the preservability before and after the development. Paragraph No. 006 of JP-A No. 10-62899.
7 to 0069, compounds represented by the general formula (I) of JP-A-10-186572 and specific examples thereof, paragraph numbers 0033 to 0052, European Patent Publication No. 0803764A.
No. 1, page 20, lines 36-56.
Among them, JP-A-9-297367 and JP-A-9-30
The mercapto-substituted heteroaromatic compounds described in JP-A No. 4875 and JP-A No. 2001-100358 are preferred.

(Description of Color Tone Agent) The photothermographic material of the invention preferably contains a color tone agent. Regarding the color toning agent, paragraph No. 00 of JP-A-10-62899.
54 to 0055, European Patent Publication No. 0803764A1, page 21, lines 23 to 48, Japanese Patent Laid-Open No. 2000-3.
No. 56317 and Japanese Patent Application No. 2000-187298, and particularly phthalazinones (phthalazinone, a phthalazinone derivative or a metal salt; for example, 4-
(1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione; phthalazinones and phthalic acids (eg phthalic acid, 4- Methylphthalic acid,
4-nitrophthalic acid, diammonium phthalate, sodium phthalate, potassium phthalate and tetrachlorophthalic anhydride) in combination; phthalazines (phthalazine, phthalazine derivatives or metal salts; eg 4- (1-naphthyl) phthalazine, 6 -Isopropylphthalazine, 6-
t-Butylflatadine, 6-chlorophthalazine, 5,7
-Dimethoxyphthalazine and 2,3-dihydrophthalazine); a combination of phthalazines and phthalic acids is preferable, and a combination of phthalazines and phthalic acids is particularly preferable. Among them, a particularly preferable combination is a combination of 6-isopropylphthalazine and phthalic acid or 4-methylphthalic acid. In the photothermographic material of the present invention, it is preferable that the coating liquid contains a toning agent as the solid dispersion of the present invention.

(Other Additives) Regarding the plasticizers and lubricants that can be used in the photosensitive layer of the present invention, JP-A-1 is used.
1-65021, paragraph No. 0117, super-high contrast agents for forming super-high contrast images, and the addition method and amount thereof, paragraph No. 0118 of the same paragraph, JP-A No. 11-223898, paragraph Nos. 0136 to 0193, and JP-A 2000- 284399
Of formula (H), formulas (1) to (3), formulas (A) and (B), and the general formula (II) described in Japanese Patent Application No. 11-91652.
Compounds of I) to (V) (specific compounds: chemical formula 21 to chemical formula 2)
4), as to the contrast enhancing agent, JP-A-11-65021.
No. 0102 and paragraph Nos. 0194 to 0195 of JP-A No. 11-223898.

To use formic acid or formate as a strong fogging substance, 5 mmol or less, more preferably 1 mol or less, per mol of silver on the side having an image forming layer containing a photosensitive silver halide.
It is preferable that the content is not more than mmol.

When an ultrahigh contrast agent is used in the photothermographic material of the present invention, it is preferable to use an acid formed by hydration of diphosphorus pentaoxide or a salt thereof in combination. Examples of the acid formed by hydration of diphosphorus pentoxide or a salt thereof include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametaline. Acid (salt)
And so on. Particularly preferably used acids formed by hydration of diphosphorus pentaoxide or salts thereof are orthophosphoric acid (salt) and hexametaphosphoric acid (salt). Specific salts include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, ammonium hexametaphosphate and the like. The amount of the acid or salt thereof formed by hydration of diphosphorus pentoxide (coating amount per 1 m ^{2 of the} light-sensitive material) may be a desired amount according to the performance such as sensitivity and fog, but is 0.1 to 500.
Preferably ^{mg / m 2, 0.5~100mg / m} 2 is more preferable.

(Explanation of Layer Structure) The photothermographic material of the invention may be provided with a surface protective layer for the purpose of preventing adhesion of the image forming layer. The surface protective layer may be a single layer,
It may have multiple layers. Regarding the surface protective layer, paragraph Nos. 0119 to 012 of JP-A No. 11-65021.
0, Japanese Patent Application No. 2000-171936.

As the binder of the surface protective layer in the present invention, gelatin is preferable, but polyvinyl alcohol (PVA) is also preferably used or used in combination.
As gelatin, inert gelatin (for example, Nitta gelatin 750), phthalated gelatin (for example, Nitta gelatin 801) and the like can be used. As PVA, paragraph number 00 of JP-A-2000-171936 is used.
Nos. 09 to 0020 are mentioned, and PVA-105 which is a completely saponified product, PVA-205 and P which is a partially saponified product.
VA-335, MP-20 of modified polyvinyl alcohol
3 (above, trade name manufactured by Kuraray Co., Ltd.) and the like are preferable. The coating amount of polyvinyl alcohol (per 1 m ^{2 of} support) of the protective layer (per layer) is 0.3 to 4.0.
preferably ^{g / m 2, 0.3~2.0g / m} 2 is more preferable.

Especially when the photothermographic material of the present invention is used for printing in which dimensional change is a problem, it is preferable to use polymer latex for the surface protective layer and the back layer.
Regarding such polymer latex, "Synthetic resin emulsion (Taira Okuda, edited by Hiroshi Inagaki, published by Kobunshi Kogyokai (1978))", "Application of synthetic latex (Takaaki Sugimura, Yasuo Kataoka, Soichi Suzuki, Keiji Kasahara, Takashi) Molecular Publishing (1993)) "," Chemistry of Synthetic Latex (Souichi Muroi, High Polymer Publishing (1970)) "and the like. Specifically, methyl methacrylate (33.5 mass%). / Ethyl acrylate (50% by mass) / methacrylic acid (16.5% by mass) copolymer latex, methyl methacrylate (47.5% by mass) / butadiene (4
7.5% by weight / itaconic acid (5% by weight) copolymer latex, ethyl acrylate / methacrylic acid copolymer latex, methyl methacrylate (58.9)
Mass%) / 2-ethylhexyl acrylate (25.4
%) / Styrene (8.6% by weight) / 2-hydroxyethyl methacrylate (5.1% by weight) / acrylic acid (2.0% by weight) copolymer latex, methyl methacrylate (64.0% by weight) / styrene Examples include latex of (9.0 mass%) / butyl acrylate (20.0 mass%) / 2-hydroxyethyl methacrylate (5.0 mass%) / acrylic acid (2.0 mass%) copolymer. Further, as the binder for the surface protective layer, a combination of polymer latexes in Japanese Patent Application No. 11-6872, the techniques described in Japanese Patent Application No. 11-143058, paragraphs 0021 to 0025, Japanese Patent Application No. 11-00258 can be used.
The technique described in paragraph numbers 0027 to 0028 of the specification of -6872 and the technique described in paragraph numbers 0023 to 0041 of the specification of Japanese Patent Application No. 10-199626 may be applied.
The ratio of the polymer latex in the surface protective layer is preferably 10% by mass or more and 90% by mass or less of the total binder, and particularly 2
0 mass% or more and 80 mass% or less are preferable. The total binder (including water-soluble polymer and latex polymer) coating amount (per 1 m ^{2 of the} support) of the surface protective layer (per layer) is preferably 0.3 to 5.0 g / m ² .
0.3 to 2.0 g / m ² is more preferable.

The temperature for preparing the coating liquid for the image forming layer in the present invention is preferably 30 ° C. or higher and 65 ° C. or lower, more preferably 35 ° C. or higher and lower than 60 ° C., and further preferably 3
It is 5 ° C or higher and 55 ° C or lower. Further, the temperature of the coating liquid for the image forming layer immediately after the addition of the polymer latex is 30 ° C or higher and 65 ° C
It is preferably maintained below.

The image forming layer of the present invention comprises one or more layers on the support. When it is composed of a single layer, it consists of an organic silver salt, a photosensitive silver halide, a reducing agent and a binder, and optionally contains additional materials such as a toning agent, a coating aid and other auxiliaries. When it is composed of two or more layers, the first image-forming layer (usually the layer adjacent to the support) contains an organic silver salt and a photosensitive silver halide, and some of them are contained in the second image-forming layer or both layers. Must contain other ingredients of. The construction of a multicolor light sensitive photothermographic material may include a combination of these two layers for each color and also within a single layer as described in US Pat. No. 4,708,928. It may include all components. In the case of multi-dye multicolor light-sensitive photothermographic materials, each emulsion layer generally contains a functional or non-functional layer between each light-sensitive layer as described in U.S. Pat. No. 4,460,681. The use of functional barrier layers keeps them distinct from each other.

The photosensitive layer of the present invention contains various dyes and pigments (for example, CI Pigment) from the viewpoints of improving color tone, preventing interference fringes during laser exposure, and preventing irradiation.
Blue 60, C.I. I. Pigment Blue
64, C.I. I. Pigment Blue 15: 6)
Can be used. About these, WO98 / 3
6322, JP-A-10-268465, 11-338098 and the like.

In the photothermographic material of the invention, the antihalation layer can be provided on the side farther from the light source than the photosensitive layer.

The photothermographic material generally has a non-photosensitive layer in addition to the photosensitive layer. The non-photosensitive layer is (1) a protective layer provided on the photosensitive layer (the side farther than the support) from the arrangement, (2) between a plurality of photosensitive layers or between the photosensitive layer and the protective layer. Can be classified into an intermediate layer provided in (3), (3) an undercoat layer provided between the photosensitive layer and the support, and (4) a back layer provided on the opposite side of the photosensitive layer. The filter layer is
The layer (1) or (2) is provided on the photosensitive material. The antihalation layer is provided on the photosensitive material as the layer (3) or (4).

Regarding the antihalation layer, paragraphs 0123 to 012 of JP-A No. 11-65021 are used.
4, JP-A-11-223898 and JP-A-9-2305.
31 gazette, the same 10-36695 gazette, the same 10-10.
No. 4779, No. 11-231457, and No. 11
No. 352625, No. 11-352626, and the like. The antihalation layer contains an antihalation dye having absorption at the exposure wavelength.
When the exposure wavelength is in the infrared region, an infrared absorbing dye may be used, and in that case, a dye having no absorption in the visible region is preferable. When using a dye having absorption in the visible region to prevent halation, it is preferable that the color of the dye does not substantially remain after image formation, and a means for erasing by heat of heat development is used. It is particularly preferable to add a heat-decolorizable dye and a base precursor to the non-photosensitive layer so that the non-photosensitive layer functions as an antihalation layer.
These techniques are described in JP-A No. 11-231457.

The amount of the decolorizing dye added depends on the use of the dye.
Set. Generally, the light when measured at the desired wavelength
It is used in an amount such that the scientific concentration (absorbance) exceeds 0.1. Optics
The concentration is preferably 0.15 to 2 and 0.2 to 1
Is more preferable. Obtaining such optical density
The amount of dye used is generally 0.001-1 g / m ²
It is a degree.

By decoloring the dye in this way, the optical density after thermal development can be lowered to 0.1 or less. Two or more kinds of decolorizable dyes may be used together in the thermally decolorizable recording material or the photothermographic material. Similarly, two or more kinds of base precursors may be used in combination. In thermal erasing using such an erasing dye and a base precursor,
A substance that lowers the melting point by 3 ° C. (deg) or more when mixed with a base precursor as described in JP-A No. 11-352626 (for example, diphenyl sulfone, 4-chlorophenyl (phenyl) sulfone), 2-naphthyl benzoate, etc. are used in combination. It is preferable from the viewpoint of thermal decoloring property.

In the present invention, a colorant having an absorption maximum at 300 to 450 nm can be added for the purpose of improving the silver tone and the change with time of the image. Such colorants are disclosed in JP-A Nos. 62-210458 and 63-104.
No. 046, No. 63-103235, No. 63-
It is described in JP-A-208846, JP-A-63-306436, JP-A-63-314535, JP-A-01-61745 and JP-A-2001-100363. Such a coloring agent is usually 0.1 mg / m ²
The back layer provided on the opposite side of the photosensitive layer is preferable as the layer to be added in the range of ˜1 g / m ² .

The photothermographic material of the present invention is a so-called single-sided photosensitive material having a photosensitive layer containing at least one silver halide emulsion on one side of a support and a back layer on the other side. Preferably there is.

(Explanation of Matting Agent) In the present invention, it is preferable to add a matting agent in order to improve the transportability. The matting agent is described in paragraph Nos. 0126 to 0127 of JP-A No. 11-65021. There is. The matting agent is preferably 1 to 400 mg / m ² , and more preferably 5 to 30 when expressed as the coating amount per 1 m ² of the light-sensitive material.
It is 0 mg / m ² . In the present invention, the shape of the matting agent may be either regular or irregular, but is preferably regular and spherical is preferred. Average particle size is 0.5-1
It is preferably 0 μm, more preferably 1.0 to
The thickness is 8.0 μm, and more preferably 2.0 to 6.0 μm. The coefficient of variation of the size distribution is 50%
It is preferably at most 40%, more preferably at most 40%, still more preferably at most 30%. Here, the coefficient of variation is (standard deviation of particle size) / (average value of particle size) × 10
It is a value represented by 0. It is also preferable to use two kinds of matting agents having a small coefficient of variation and having a ratio of average particle diameters of more than 3.

The matteness of the emulsion surface may be any as long as stardust failure does not occur, but the Beck smoothness is 30.
Seconds or more and 2000 seconds or less are preferable, and 40 seconds or more and 15
00 seconds or less is preferable. The Beck's smoothness can be easily determined according to Japanese Industrial Standard (JIS) P8119 "Smoothness test method for Beck tester for paper and board" and TAPPI standard method T479.

In the present invention, the Bekk smoothness of the back layer is preferably 1200 seconds or less and 10 seconds or more, 800 seconds or less and 20 seconds or more, and more preferably 500 seconds or less and 40 seconds or more.

In the present invention, the matting agent is preferably contained in the outermost surface layer of the light-sensitive material, the layer functioning as the outermost surface layer, or the layer close to the outer surface, and the layer acting as a so-called protective layer. It is preferably contained.

The back layer applicable to the present invention is described in paragraph No. 01 of JP-A No. 11-65021.
28-0130.

The photothermographic material of the present invention preferably has a film surface pH of 7.0 or less before heat development, and more preferably 6.6 or less. The lower limit is not particularly limited, but is about 3. Most preferred pH range is 4 to
The range is 6.2. From the viewpoint of reducing the film surface pH, it is preferable to use an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, or a volatile base such as ammonia for adjusting the film surface pH. Ammonia is particularly volatile so that it can be removed before the coating step or heat development, which is preferable for achieving a low film surface pH. It is also preferable to use a non-volatile base such as sodium hydroxide, potassium hydroxide or lithium hydroxide in combination with ammonia. In addition, the measuring method of the film surface pH is described in Japanese Patent Application No. 11-8.
No. 7297, paragraph 0123.

A hardener may be used for each layer such as the photosensitive layer, the protective layer and the back layer in the photothermographic material of the present invention. Examples of hardeners include T.I. H. By James, "T
HETHEORY OF THE PHOTOGRAP
HIC PROCESS FOURTH EDITION
N "(Macmillan PublishingC
o. , Inc. 1977, pp. 77-87. Chromium alum, 2,4-dichloro-6-hydroxy-s-triazine sodium salt, N, N-ethylenebis (vinylsulfonacetamide), N , N-propylenebis (vinylsulfonacetamide), polyvalent metal ions described on page 78 of the same book,
U.S. Pat. No. 4,281,060, JP 6-20
Polyisocyanates such as 8193, epoxy compounds such as US Pat. No. 4,791,042, and vinyl sulfone compounds such as JP-A-62-89048 are preferably used.

The hardener is added as a solution, and the time of adding this solution to the protective layer coating solution is from 180 minutes before to just before coating, preferably from 60 minutes before to 10 seconds before coating. The mixing conditions are not particularly limited as long as the effects of the present invention are sufficiently exhibited. Specific mixing methods include a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is set to a desired time, and N. Harnby, M .; F. Edward
s, A.S. W. There is a method using a static mixer described in Chapter 8 of Nienow's "Liquid Mixing Technology" translated by Koji Takahashi (published by Nikkan Kogyo Shimbun, 1989).

The surfactant applicable to the photothermographic material of the invention is described in paragraph No. 0132 of JP-A No. 11-65021, and the solvent is described in paragraph No. 013.
Paragraph No. 0134 of the same publication for the support, Paragraph No. 0135 of the same publication for the antistatic or conductive layer, and Paragraph No. 01 of the same publication for the method of obtaining a color image.
36, the paragraphs 0061 to 0064 of JP-A-11-84573 and Japanese Patent Application No. 11-106.
Paragraph Nos. 0049 to 0062 of 881 publication are described.

The photothermographic material of the invention preferably has a conductive layer containing a metal oxide. As the conductive material of the conductive layer, a metal oxide in which oxygen defects and foreign metal atoms are introduced into the metal oxide to enhance the conductivity is preferably used. Examples of metal oxides are ZnO, TiO ₂ , SnO ₂
Is preferred, and addition of Al and In to ZnO ₂ and S
It is preferable to add Sb, Nb, P, a halogen element or the like to nO ₂ , and add Nb or Ta to TiO ₂ . In particular, SnO ₂ with Sb added is preferable. The addition amount of the hetero atom is preferably in the range of 0.01 to 30 mol%,
The range of 0.1 to 10 mol% is more preferable. The shape of the metal oxide may be spherical, acicular, or plate-like, but in terms of the effect of imparting conductivity, the major axis / uniaxial ratio is 2.0 or more, preferably 3.0 to 50 acicular particles. Good. The amount of the metal oxide used is preferably in the range of 1 mg / m to 1000 mg / m ² , more preferably in the range of 10 mg / m to 500 mg / m ² , and further preferably in the range of 20 mg / m to 200 mg / m ^2.
It is in the range of ² . The conductive layer in the photothermographic material of the invention may be provided on either the emulsion surface side or the back surface side, but it is preferably provided between the support and the back layer. As a specific example of the conductive layer, Japanese Patent Laid-Open No. 7-295146 can be used.
Japanese Patent Laid-Open No. 11-223901.

In the photothermographic material of the present invention, it is preferable to use a fluorine type surfactant. Specific examples of the fluorinated surfactant include JP-A-10-19798.
5, JP-A 2000-19680, JP-A 20
The compounds described in, for example, 00-214554 are cited. Further, the polymeric fluorine-based surfactant described in JP-A-9-281636 is also preferably used. In the present invention, it is particularly preferable to use the fluorinated surfactant described in Japanese Patent Application No. 2000-206560.

(Description of Support) The support in the photothermographic material of the present invention may be transparent or opaque, but is preferably transparent. As the transparent support, a polyester heat-treated in a temperature range of 130 to 185 ° C. in order to alleviate internal strain remaining in the film during biaxial stretching and eliminate heat shrinkage strain generated during heat development treatment, In particular, polyethylene terephthalate is preferably used. In the case of a heat-developable photosensitive material for medical use, the transparent support may be colored with a blue dye (for example, dye-1 described in Examples of JP-A-8-240877) or may be uncolored. For the support, JP-A-11-845 is used.
No. 74 publication, water-soluble polyester, 10-18656
No. 5, styrene-butadiene copolymer, JP 2000
It is preferable to apply an undercoating technique such as the vinylidene chloride copolymer described in paragraphs 0063 to 0080 of Japanese Patent Application No. 39684/1999 and Japanese Patent Application No. 11-106881. Further, regarding the antistatic layer or the undercoat, JP-A-56-1434
30 gazette, the same 56-143431 gazette, the same 58-6.
2646, 56-120519, and JP-A-11
-84573, paragraphs 0040 to 0051, U.S. Pat. No. 5,575,957, JP-A 11-2
The technique described in paragraph numbers 0078 to 0084 of the specification of 23898 can be applied.

(Others) The photothermographic material of the present invention is preferably a monosheet type (a type capable of forming an image on the photothermographic material without using another sheet such as an image receiving material). .

An antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber or a coating aid may be further added to the photothermographic material of the invention. Various additives are added to either the photosensitive layer or the non-photosensitive layer. Regarding them, WO98 / 36322, EP803764A1,
Reference can be made to JP-A Nos. 10-186567 and 10-18568.

(Production of Photothermographic Material) The photothermographic material of the invention may be applied by any method. Specifically, extrusion coating, slide coating, curtain coating, dip coating,
Various coating operations have been used, including knife coating, flow coating, or extrusion coating using a hopper of the type described in US Pat. Kistler, P
ett M. "LIQUI" by Schweizer
D FILM COATING "(CHAPMAN &
Extrusion coating or slide coating described on pages 399 to 536 of HALL, 1997) is preferably used, and slide coating is particularly preferably used. An example of the shape of a slide coater used for slide coating is shown in Fig. 11b. In 1. If desired, the method described on pages 399 to 536 of the same document, US Pat.
Two or more layers can be coated simultaneously by the methods described in 61,791 and GB 837,095.

The organic silver salt-containing layer coating solution in the photothermographic material of the invention is preferably a so-called thixotropic fluid. This technique is disclosed in JP-A-11-525.
No. 09 can be referred to. The organic silver salt-containing layer coating solution of the present invention has a viscosity at a shear rate of 0.1 S ⁻¹ of preferably 400 mPa · s or more and 100,000 mPa · s or less, more preferably 500 mPa · s or more 2.
It is 30,000 mPa · s or less. Also, a shear rate of 10
At 00S- ¹ , more than 1mPa ・ s and more than 200mPa ・ s
The following is preferable, and more preferably 5 mPa · s or more 8
It is 0 mPa · s or less.

Techniques applicable to the photothermographic material of the present invention include EP803764A1 and EP88.
3022A1, WO98 / 36322, JP-A-56
-62648, 58-62644, JP-A-9-4
3766, 9-281637, 9-297367
No. 9, No. 9-304869, No. 9-31405, No. 9-329865, No. 10-10669, No. 10-.
62899, 10-69023, 10-186.
No. 568, No. 10-90823, No. 10-17106.
No. 3, No. 10-186565, No. 10-186567
No. 10-186569-No. 10-186572
No. 10-197974 and No. 10-197982.
No. 10, No. 10-197983, No. 10-197985 to No. 10-197987, No. 10-207001,
10-207004, 10-221807, 10-282601, 10-288823, 1
0-288824, 10-307365, 10
-312038, 10-339934, 11-
No. 7100, No. 11-15105, No. 11-2420
No. 0, No. 11-24201, No. 11-30832,
11-84574, 11-65021, 11
-1095547, 11-125880, 11-
129629, 11-133536 to 11-1
No. 33539, No. 11-133542, No. 11-13.
No. 3543, No. 11-223898, No. 11-352.
No. 627, No. 11-305377, No. 11-3053.
78, 11-305384, 11-30538.
No. 0, No. 11-316435, No. 11-327076.
No. 11-338096 and No. 11-338098.
No. 11-338099 and 11-343420
No. 2000-187298, No. 2000-10
229, 2000-47345, 2000-2
06642, 2000-98530, 2000
-98531, 2000-112059, 20
00-112060, 2000-112104,
No. 2000-112064, No. 2000-17193
Each publication of No. 6 is also mentioned.

(Explanation of Packing Material) The light-sensitive material of the present invention has a low oxygen permeability and / or a low moisture permeability in order to suppress fluctuations in photographic performance during raw storage or to improve curl, curl and the like. It is preferable to wrap with a packaging material.
Oxygen permeability is 50ml / atm ・ m ²・ day at 25 ℃
It is preferably below, more preferably 10 ml /
atm · m ² · day or less, more preferably 1.0 m
It is 1 / atm · m ² · day or less. Water permeability is 1
It is preferably 0 g / atm · m ² · day or less, more preferably 5 g / atm · m ² · day or less,
More preferably, it is 1 g / atm · m ² · day or less. Specific examples of the packaging material having a low oxygen permeability and / or a low moisture permeability include, for example, JP-A-8-254793.
The packaging materials described in Japanese Patent Publication No. 2000-206653 and Japanese Patent Application Laid-Open No. 2000-206653 are mentioned.

(Explanation of Thermal Development) The photothermographic material of the present invention may be developed by any method, but it is usually developed by heating the photothermographic material exposed imagewise.
The preferred developing temperature is 80 to 250 ° C, preferably 100 to 140 ° C, more preferably 110 to 1 ° C.
It is 30 ° C. The development time is preferably 1 to 60 seconds, more preferably 3 to 30 seconds, and further preferably 5 to
25 seconds and 7 to 15 seconds are particularly preferable.

As a method of heat development, a drum type heater,
Any plate type heater may be used, but the plate heater system is more preferable. The heat development method using a plate heater method is preferably the method described in JP-A No. 11-133572, and a visible image is obtained by bringing a latent image-formed photothermographic material into contact with heating means in the thermal development section. In the heat developing apparatus, the heating means is composed of a plate heater, and a plurality of pressing rollers are arranged to face each other along one surface of the plate heater, and the pressing roller is arranged between the pressing roller and the plate heater. It is a thermal developing device characterized by performing thermal development by passing a photothermographic material. It is preferable to divide the plate heater into 2 to 6 stages and lower the temperature of the tip portion by about 1 to 10 ° C.
For example, four sets of plate heaters that can be independently temperature controlled are used, and 112 ° C, 119 ° C, 121 ° C, and 12 ° C, respectively.
An example of controlling the temperature to 0 ° C. is given. Such a method is also described in JP-A No. 54-30032, and it is possible to exclude the water content and the organic solvent contained in the photothermographic material from the outside of the system, and to rapidly perform the heat development. It is also possible to suppress changes in the shape of the support of the photothermographic material due to heating of the photosensitive material.

The light-sensitive material of the present invention may be exposed by any method, but a laser beam is preferable as an exposure light source.
The laser light according to the present invention includes a gas laser (Ar
⁺ , He-Ne), YAG laser, dye laser, semiconductor laser and the like are preferable. Alternatively, a semiconductor laser and a second harmonic wave generating element may be used. Preferred is a gas of red to infrared emission or a semiconductor laser.

Fuji Medical Dry Laser Imager FM-DP L can be mentioned as a medical laser imager provided with an exposure section and a heat development section. Regarding FM-DP L, Fuji Medic
al Review No. 8, page 39-55
Needless to say, those techniques are applied as a laser imager for the photothermographic material of the present invention. It can also be applied as a photothermographic material for a laser imager in "AD network" proposed by Fuji Medical System as a network system adapted to the DICOM standard.

The photothermographic material of the present invention forms a black and white image by a silver image, and is used for medical diagnosis, photothermographic material for industrial photography, photothermographic material for printing, COM.
It is preferably used as a photothermographic material.

[0242]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 Solid Dispersion << Preparation of Solid Dispersion-1 of Organic Polyhalogen Compound >> Modified Polyvinyl Alcohol (Kovara MP Co., Ltd. Poval MP)
203 kg of a 10 mass% aqueous solution of 20%, sodium triisopropylnaphthalene sulfonate of 20 mass% aqueous solution 0.4 kg, and water of 4 kg are mixed with a propeller stirrer at room temperature to prepare a solution of organic polyhalogen compound-1 [Exemplified compound example (H-8)] Add 10 kg over about 20 minutes,
A slurry liquid was prepared. This slurry was sent by a diaphragm pump and dispersed for 5 hours by a pass method in a horizontal sand mill (UVM-2: manufactured by AIMEX Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. After filtering with a filter FE-10 manufactured by Fuji Photo Film Co., Ltd. (polypropylene pore size filter 10.0 μm), the dispersion was heat treated at 40 ° C. for 5 hours, and then benzoisothiazolinone sodium salt 0.2 g and water were added. Prepared so that the concentration of the organic polyhalogen compound is 30% by mass, and filtered with Fuji Photo Film Co., Ltd. filter FC-3 (polypropylene pore diameter 3.0 μm filter).
Foreign substances such as dust were removed and stored. Details of the obtained organic polyhalogen compound solid dispersion-1 (hereinafter sometimes referred to as "organic polyhalogen compound dispersion-1") [median diameter, viscosity of solid dispersion (10 ° C and 25 ° C) ), The specific gravity of the dispersoid, the average sedimentation velocity of the dispersoid (10
C. and 25.degree. C.), etc.] are shown in Tables 1 and 2.

<< Solid Dispersion of Organic Polyhalogen Compound--
Preparation of 2 to 24 >> In the preparation of the solid dispersion-1 of the organic polyhalogen compound, as shown in Table 1, the median diameter is changed by changing the dispersion time to change the kind and concentration of the organic polyhalogen compound or the dispersant. By changing the viscosity of the solid dispersion and changing the specific gravity of the dispersoid by changing the type of the organic polyhalogen compound, in the same manner as in the preparation of the organic polyhalogen compound dispersion-1. Solid Dispersions-2 to 24 were prepared. Details of the obtained solid dispersion are shown in Tables 1 and 2.

<Evaluation of Solid Dispersion> Each of the obtained solid dispersions 1 to 24 was placed in a glass column having a length of 30 cm and stored under the following storage conditions to 3 mg of the upper and lower parts of the container. Then, the concentration was measured by HPLC and evaluated according to the following criteria.

<Storage condition> Storage condition: Refrigerated (8 ℃) Storage for 1 month Storage condition: Refrigerated (8 ℃) storage 3 months Storage condition: 1 month storage at room temperature Storage conditions: storage at room temperature for 3 months

<Criteria> ◯: The concentration difference between the upper part and the lower part in the container is within 2%,
No sediment in the container. Δ: The concentration difference between the upper part and the lower part in the container is within 2 to 5%, and there is a slight sediment in the container, but there is no practical problem. X: The difference in concentration between the upper part and the lower part in the container is 5% or more,
Sediment is clearly visible in the container.

[0248]

[Table 1]

[0249]

[Table 2]

As shown in Table 2, the average sedimentation velocity (v ₂₆ ) of the dispersoid at 26 ° C. was 5.0 × 10 ^-6 mm / se.
c or less, and the average sedimentation velocity (v ₁₀ ) of the dispersoid at 10 ° C. is 2.5 × 10 ⁻⁶ mm / sec or less, the solid dispersion of the polyhalogen compound has a concentration change in the storage container. It was found to be small and excellent in stability over time.

(Example 2) Photothermographic material (preparation of PET support) Using terephthalic acid and ethylene glycol, an intrinsic viscosity IV = 0.66 (phenol / tetrachloroethane = 6 /) according to a conventional method. 25 out of 4 (mass ratio)
PET (measured at ° C.) Was obtained. After pelletizing this 1
After drying at 30 ° C. for 4 hours, melting at 300 ° C., extrusion from a T-die and rapid cooling, an unstretched film having a thickness such that the film thickness after heat setting was 175 μm was produced.

This is set to 3.3 by using rolls having different peripheral speeds.
The film was longitudinally stretched twice and then horizontally stretched 4.5 times with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. After that, heat setting was carried out at 240 ° C. for 20 seconds, and then relaxation was carried out in the lateral direction by 4% at the same temperature. After this, after slitting the chuck part of the tenter, both ends are knurled and 4
The roll was wound at kg / cm ² to obtain a roll having a thickness of 175 μm.

(Surface corona treatment) Both sides of the support were treated at 20 m / min at room temperature using a solid state corona treatment machine 6KVA model manufactured by Pillar Co. From the readings of current and voltage at this time, 0.375 kV was applied to the support.
・ It was found that the treatment of A · min / m ² was performed.
The processing frequency at this time was 9.6 kHz, and the electrode and dielectric
The gap clearance of the groove was 1.6 mm.

[0254] (Preparation of undercoat support) (1) Preparation of undercoat layer coating liquid Prescription (for undercoat layer on photosensitive layer)   Takamatsu Yushi Co., Ltd. pestle resin A-520 (30 mass% solution) 59g   Polyethylene glycol monononyl phenyl ether        (Average number of ethylene oxide = 8.5) 10 mass% solution 5.4g   Soken Chemical Co., Ltd.MP-1000 (polymer particles, average particle size 0.4 μm) 0.91 g   Distilled water 935ml

[0255] Prescription (for back surface first layer)   Styrene-butadiene copolymer latex 158g   (Solid content 40 mass%, styrene / butadiene weight ratio = 68/32)   2,4-dichloro-6-hydroxy-S-     Triazine sodium salt 8 mass% aqueous solution 20g   10 ml of 1% by mass aqueous solution of sodium laurylbenzene sulfonate   Distilled water 854ml

Formulation (for second layer on back side) SnO ₂ / SbO (9/1 mass ratio, average particle size 0.038 μm, 17 mass% dispersion) 84 g Gelatin (10 mass% aqueous solution) 89.2 g Shin-Etsu Chemical Co., Ltd. ) Metrose TC-5 (2% by mass aqueous solution) 8.6 g Soken Chemical Industry Co., Ltd. MP-1000 0.01 g 1% by mass aqueous solution of sodium dodecylbenzenesulfonate 10 ml NaOH (1% by mass) 6 ml Proxel (manufactured by ICI) 1 ml Distilled water 805ml

Both sides of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm were subjected to the corona discharge treatment, and then one side (photosensitive layer side) of the undercoat coating solution formulation was coated with a wire bar to give a wet coating amount of 6 .6
Apply 180 ml / m ² (per surface)
Dry at 5 ° C for 5 minutes, then apply the undercoat coating solution formulation to the back surface (back surface) with a wire bar so that the wet coating amount is 5.7 ml / m ^2, and dry at 180 ° C for 5 minutes. Wet coating amount of the above-mentioned undercoating liquid formulation on the back surface (back surface) with a wire bar is 7.7 ml / m 2.
^It was coated so as to be ² and dried at 180 ° C. for 6 minutes to prepare an undercoat support.

(Preparation of coating liquid for back surface) (Preparation of solid fine particle dispersion liquid (a) of base precursor)
64 g of base precursor compound-1, 28 g of diphenyl sulfone, and Demol N, a surfactant manufactured by Kao Corporation
10 g was mixed with 220 ml of distilled water, the mixture was bead-dispersed using a sand mill (1/4 Gallon sand grinder mill, manufactured by AIMEX Co., Ltd.), and a solid fine particle dispersion liquid of a base precursor compound having an average particle diameter of 0.2 μm. (A) was obtained.

(Preparation of Dye Solid Fine Particle Dispersion) 9.6 g of cyanine dye compound-1 and 5.8 g of sodium p-dodecylbenzenesulfonate were mixed with 305 ml of distilled water, and the mixture was sand-milled (1/4 Gallon sand). Beads were dispersed using a grinder mill, manufactured by Imex Co., Ltd. to obtain a dye solid fine particle dispersion having an average particle diameter of 0.2 μm.

(Preparation of coating liquid for antihalation layer) 17 g of gelatin, 9.6 g of polyacrylamide, 56 g of solid fine particle dispersion (a) of the above base precursor, 50 g of solid dye fine particle dispersion described above, and monodispersed polymethylmethacrylate fine particles (average) Particle size 8 μm, particle size standard deviation 0.
4) 1.5 g, benzoisothiazolinone 0.03 g, sodium polyethylene sulfonate 2.2 g, blue dye compound-1 0.1 g, yellow dye compound-1 0.1 g,
844 ml of water was mixed to prepare a coating liquid for antihalation layer.

(Preparation of Back Surface Protective Layer Coating Solution)
Keep warm at 0 ° C., gelatin 50 g, sodium polystyrene sulfonate 0.2 g, N, N-ethylene bis (vinyl sulfone acetamide) 2.4 g, sodium t-octylphenoxyethoxyethane sulfonate 1 g, benzoisothiazolinone 30 mg, fluorine System surfactant (F-
1: N-perfluorooctylsulfonyl-N-propylalanine potassium salt) 37 mg, fluorine-based surfactant (F-2: polyethylene glycol mono (N-perfluorooctylsulfonyl-N-propyl-2-aminoethyl) ether [ Ethylene oxide average degree of polymerization 1
5]) 150 mg, fluorinated surfactant (F-3) 64
mg, fluorine warning surface active agent (F-4) 32 mg, acrylic acid / ethyl acrylate copolymer (copolymerization weight ratio 5 /
95) 8.8 g, aerosol OT (manufactured by American Cyanamid Co., Ltd.) 0.6 g, liquid paraffin emulsion as liquid paraffin 1.8 g, and water 950 ml were mixed to obtain a back surface protective layer coating liquid.

(Preparation of silver halide emulsion) << Preparation of silver halide emulsion 1 >> 1 to 1421 ml of distilled water
3.1 ml of a mass% potassium bromide solution was added, and a further 0.1.
While stirring a liquid containing 3.5 ml of 5 mol / L sulfuric acid and 31.7 g of phthalated gelatin in a reaction vessel made of stainless steel, the liquid temperature was maintained at 30 ° C., and distilled water was added to 22.22 g of silver nitrate. Solution A diluted to 95.4 ml, potassium bromide (15.3 g) and potassium iodide (0.8 g), and solution B diluted to a volume of 97.4 ml with distilled water were added at a constant flow rate over 45 seconds. Then, 10 ml of a 3.5 mass% hydrogen peroxide aqueous solution was added, and 10.8 ml of a 10 mass% aqueous solution of benzimidazole was further added. Further, distilled water was added to 51.86 g of silver nitrate to obtain 317.5 m.
The total amount of Solution C diluted to 1 with 44.2 g of potassium bromide and 2.2 g of potassium iodide to a volume of 400 ml with distilled water was added over 20 minutes at a constant flow rate to obtain Solution D. Was added by the controlled double jet method while maintaining pAg at 8.1. 1 per mole of silver
10 ^times from the beginning of adding solution C and solution D of hexachloroiridium (III) acid potassium salt to a concentration of × 10 ^-4 mol
After a minute, the whole amount was added. Further, 5 seconds after the addition of the solution C was completed, an aqueous solution of potassium hexacyanoferrate (II) cyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 with sulfuric acid at a concentration of 0.5 mol / L, stirring was stopped, and sedimentation /
A desalting / washing process was performed. The pH was adjusted to 5.9 with sodium hydroxide having a concentration of 1 mol / L, and pAg 8.0 was obtained.
To prepare a silver halide dispersion.

While stirring the above silver halide dispersion, 3
Maintaining at 8 ° C., 5 ml of 0.34% by mass of 1,2-benzisothiazolin-3-one in methanol was added,
After 40 minutes, the molar ratio of spectral sensitizing dye A and sensitizing dye B was 1:
The methanol solution of 1 was added in an amount of 1.2 × 10 ⁻³ mol as a total of the sensitizing dye A and the sensitizing dye B per mol of silver, and 1 minute later, the temperature was raised to 47 ° C. After 20 minutes of heating, 7.6 × 10 ⁻⁵ mol of sodium benzenethiosulfonate was added to 1 mol of silver in a methanol solution, and after 5 minutes, tellurium sensitizer B was added in a methanol solution to 2.10 per mol of silver. 9 × 10 ⁻⁴ mol was added and the mixture was aged for 91 minutes. N, N'-dihydroxy-
1.3 ml of 0.8 mass% methanol solution of N "-diethylmelamine was added, and after 4 minutes, 5-methyl-2-
Mercaptobenzimidazole in methanol solution with silver 1
4.8 × 10 ^-3 moles per mole and 1-phenyl-2-
Heptyl-5-mercapto-1,3,4-triazole was added as a silver halide emulsion 1 by adding 5.4 × 10 ⁻³ mol with respect to 1 mol of silver in a methanol solution.

The grains in the obtained silver halide emulsion had an average equivalent spherical diameter of 0.042 μm and a variation coefficient of equivalent spherical diameter of 20%.
The silver iodobromide grains contained 3.5 mol% of iodine. The particle size and the like were determined from the average of 1000 particles using an electron microscope. The {100} plane ratio of this grain was determined to be 80% using the Kubelka-Munk method.

<< Preparation of Silver Halide Emulsion 2 >> In the preparation of silver halide emulsion 1, the liquid temperature at the time of grain formation was set to 4 ° C.
The temperature was changed to 7 ° C., the solution B was changed to dilute potassium bromide 15.9 g with distilled water to a volume of 97.4 ml, and the solution D was potassium bromide 45.8 g with distilled water to a volume of 400 m.
A silver halide emulsion 2 was prepared in the same manner except that the solution C was diluted to 1, the solution C was added for 30 minutes, and potassium hexacyanoferrate (II) was removed. Precipitation / desalting / washing / dispersion were carried out in the same manner as in the silver halide emulsion 1. Furthermore, the addition amount of the methanol solution having a molar ratio of the spectral sensitizing dye A to the spectral sensitizing dye B of 1: 1 is 7.5 × 10 ⁻⁴ mol as the total amount of the sensitizing dye A and the sensitizing dye B per mol of silver. ,
Tellurium sensitizer B is added in an amount of 1.1 × 10 per mol of silver.
^-4 mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole, 3.3 mol per mol of silver.
Spectral sensitization, chemical sensitization and 5-methyl-2-mercaptobenzimidazole, 1-phenyl-2-heptyl-5-mercapto-1,3, were carried out in the same manner as in Emulsion 1 except that the amount was changed to × 10 ^-3 mol. 4-Triazole was added to obtain Silver Halide Emulsion 2. The emulsion grains of the silver halide emulsion 2 were pure silver bromide cubic grains having an average equivalent sphere diameter of 0.080 μm and a variation coefficient of the equivalent sphere diameter of 20%.

<< Preparation of Silver Halide Emulsion 3 >> In the preparation of silver halide emulsion 1, the liquid temperature at the time of grain formation was 30 ° C. for 2 hours.
Silver halide emulsion 3 was similarly prepared except that the temperature was changed to 7 ° C.
Was prepared. Further, precipitation / desalting / washing / dispersion were carried out in the same manner as in the silver halide emulsion 1. The molar ratio of the spectral sensitizing dye A and the spectral sensitizing dye B was 1: 1 as a solid dispersion (gelatin aqueous solution), and the addition amount was 6 × 10 ⁻ as the total amount of the sensitizing dye A and the sensitizing dye B per 1 mol of silver. ^A silver halide emulsion 3 was obtained in the same manner as the emulsion 1, except that the amount of the ³ mol tellurium sensitizer B added was changed to 5.2 × 10 ⁻⁴ mol per mol of silver.
The emulsion grains of the silver halide emulsion 3 have an average equivalent spherical diameter of 0.0
The silver iodobromide grains were 34 μm in size and uniformly contained 3.5 mol% of iodine having a coefficient of variation of equivalent spherical diameter of 20%.

<< Preparation of Mixed Emulsion A for Coating Liquid >> 70% by mass of silver halide emulsion 1, 15% by mass of silver halide emulsion 2 and 15% by mass of silver halide emulsion 3 were dissolved, and benzothiazolium iodine was dissolved. Id was added as an aqueous solution of 1% by mass at 7 × 10 ⁻³ mol per mol of silver. Further, the content of silver halide is 38.2 as silver per 1 kg of the mixed emulsion for coating liquid.
Water was added so as to be g.

(Preparation of Organic Silver Salt Dispersion) Behenic Acid (Henkel: Product Name Edenor C22-85R) 8
7.6 kg, distilled water 423 L, 5 mol / L concentration of Na
49.2 L of OH aqueous solution, 12 t-butyl alcohol
0 L was mixed and stirred at 75 ° C. for 1 hour for reaction to obtain a sodium behenate solution. Separately, 40.4 kg of silver nitrate
Prepare 206.2 L of aqueous solution (pH 4.0) of 10 ° C.
It was kept warm at. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept warm at 30 ° C., and while stirring sufficiently, the total amount of the sodium behenate solution and the total amount of the silver nitrate aqueous solution were each kept constant at 93 minutes 15 seconds. And 9
Added over 0 minutes. At this time, only the silver nitrate aqueous solution is added for 11 minutes after the addition of the silver nitrate aqueous solution is started,
Then, the sodium behenate solution was started to be added, and only the sodium behenate solution was added for 14 minutes and 15 seconds after the addition of the silver nitrate aqueous solution was completed. At this time, the temperature inside the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The piping of the addition system of the sodium behenate solution was kept warm by circulating hot water outside the double pipe, and the liquid temperature at the outlet of the addition nozzle tip was adjusted to 75 ° C. Further, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double tube. The position of addition of the sodium behenate solution and the position of addition of the aqueous solution of silver nitrate were symmetrically arranged around the stirring axis, and the height was adjusted so as not to come into contact with the reaction solution.

After the addition of the sodium behenate solution was completed, the mixture was left to stir at the same temperature for 20 minutes, and the mixture was cooled to 35 minutes over 30 minutes.
The temperature was raised to 0 ° C., and then aged for 210 minutes. Immediately after completion of the aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of the filtered water reached 30 μS / cm. Thus, an organic silver salt was obtained. The obtained solid content was stored as a wet cake without being dried.

The morphology of the obtained silver behenate particles was evaluated by electron microscopic photography, and the average value was a = 0.14 μ.
It was a flaky crystal having m, b = 0.4 μm, c = 0.6 μm, an average aspect ratio of 5.2, an average equivalent sphere diameter of 0.52 μm, and a variation coefficient of the equivalent sphere diameter of 15%. (A, b, c are the rules of the text)

For a wet cake having a dry solid content of 260 kg, polyvinyl alcohol (trade name: PVA-2) was used.
17) Add 19.3 kg and water to bring the total amount to 1000
After being made into kg, it is slurried with a dissolver blade, and further a pipeline mixer (PM-10 type manufactured by Mizuho Industry Co., Ltd.)
It was pre-dispersed in.

Next, the pressure of the disperser (trade name: Microfluidizer M-610, manufactured by Microfluidex International Corporation, using Z type interaction chamber) of the predispersed stock solution was set to 1
It was adjusted to 260 kg / cm ² and treated three times to obtain a silver behenate dispersion. For the cooling operation, a spiral heat exchanger was attached before and after the interaction chamber, and the dispersion temperature was set to 18 ° C. by adjusting the temperature of the refrigerant.

(Preparation of Reducing Agent Dispersion) << Preparation of Reducing Agent Complex-1 Dispersion >> Reducing Agent Complex-1 (6
6'-di-t-butyl-4,4'-dimethyl-2,
2'-butylidene diphenol) and 1: 1 complex of triphenylphosphine oxide) 10 kg, triphenylphosphine oxide 0.12 kg and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10
10 kg of water was added to 16 kg of a mass% aqueous solution and mixed well to obtain a slurry. This slurry was sent by a diaphragm pump and dispersed in a horizontal sand mill (UVM-2: manufactured by AIMEX Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm for 4 hours and 30 minutes, and then benzoisothiazolinone sodium salt. 0.2 g and water were added to prepare a reducing agent having a concentration of 22% by mass to obtain a reducing agent complex-1 dispersion. The reducing agent complex particles contained in the thus obtained reducing agent complex dispersion had a median diameter of 0.45 μm and a maximum particle diameter of 1.4 μm or less. The obtained reducing agent complex dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign matters such as dust and stored.

<< Preparation of Reducing Agent-2 Dispersion >> Reducing Agent-2
(6,6'-di-t-butyl-4,4'-dimethyl-
2,2'-butylidene diphenol) 10 kg and denatured polyvinyl alcohol (Kuraray Co., Ltd., Poval MP2)
10 kg of water was added to 16 kg of the 10 mass% aqueous solution of No. 03) and mixed well to form a slurry. This slurry was sent by a diaphragm pump and filled with zirconia beads having an average diameter of 0.5 mm. A horizontal sand mill (UVM-
2: Disperse with IMEX Co., Ltd. for 3 hours and 30 minutes, and then add 0.2 g of benzoisothiazolinone sodium salt and water to prepare a reducing agent having a concentration of 25% by mass. Two dispersions were obtained. The reducing agent particles contained in the thus obtained reducing agent dispersion have a median diameter of 0.40 μm,
The maximum particle size was 1.5 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign matters such as dust and stored.

(Preparation of Hydrogen Bonding Compound-1 Dispersion) Hydrogen Bonding Compound-1 (Tri (4-t-butylphenyl))
10 kg of water was added to 16 kg of a 10 mass% aqueous solution of phosphine oxide) and modified polyvinyl alcohol (Kovara MP203, Poval MP203), and mixed well to form a slurry. This slurry was sent by a diaphragm pump and dispersed for 3 hours and 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt. 0.2 g and water were added to the mixture to prepare a hydrogen-bonding compound having a concentration of 25% by mass to obtain a hydrogen-bonding compound-1 dispersion. The hydrogen-bonding compound particles contained in the hydrogen-bonding compound dispersion thus obtained,
The median diameter was 0.35 μm and the maximum particle diameter was 1.5 μm or less. The resulting hydrogen-bonding compound dispersion had a pore size of 3.
Filter with a polypropylene filter of 0 μm,
Foreign substances such as dust were removed and stored.

(Preparation of Development Accelerator Dispersion) << Preparation of Development Accelerator-1 Dispersion >>
10 kg of water and 20 kg of a 10 mass% aqueous solution of denatured polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval MP203) were added and mixed well to form a slurry. This slurry was sent by a diaphragm pump, and a horizontal sand mill (UVM-2: manufactured by IMEX Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm was used for 3 hours 3 hours
After dispersion for 0 minutes, 0.2 g of benzoisothiazolinone sodium salt and water were added to give a development accelerator concentration of 20% by mass.
To obtain a development accelerator-1 dispersion. The development accelerator particles contained in the thus obtained development accelerator dispersion had a median diameter of 0.48 μm and a maximum particle diameter of 1.4 μm or less. The resulting development accelerator dispersion has a pore size of 3.0 μm.
m polypropylene filter to remove foreign matters such as dust, and stored.

<Preparation of Development Accelerator-2 Dispersion> The solid dispersion of Development Accelerator-2 was dispersed in the same manner as in Development Accelerator-1 to obtain a 20% by mass dispersion.

<Preparation of Development Accelerator-3 Dispersion> The solid dispersion of Development Accelerator-3 was dispersed in the same manner as in Development Accelerator-1 to obtain a 20% by mass dispersion.

(Preparation of color tone adjusting agent dispersion) Color tone adjusting agent-
The solid dispersion 1 was dispersed in the same manner as in the development accelerator-1 to obtain a 20% by mass dispersion liquid.

(Preparation of Polyhalogen Compound Dispersion) Solid dispersion-1 of organic polyhalogen compound prepared in Example 1 (hereinafter referred to as "organic polyhalogen compound-1 dispersion") and organic polyhalogen compound. Solid dispersion-2
4 (hereinafter referred to as "organic polyhalogen compound-24 dispersion") was used.

<< Preparation of Phthalazine Compound-1 Solution >> 8k
Denatured polyvinyl alcohol MP20 manufactured by Kuraray Co., Ltd.
3 was dissolved in 174.57 kg of water, and then 3.15 kg of a 20 mass% aqueous solution of sodium triisopropylnaphthalenesulfonate and 14.28 kg of a 70 mass% aqueous solution of phthalazine compound-1 (6-isopropylphthalazine) were added, and phthalazine was added. A 5 mass% solution of compound-1 was prepared.

(Preparation of mercapto compound) << Preparation of mercapto compound-1 aqueous solution >> 7 g of mercapto compound-1 (1- (3-sulfophenyl) -5-mercaptotetrazole sodium salt) was dissolved in 993 g of water to give 0.7 A mass% aqueous solution was used.

<< Preparation of Mercapto Compound-2 Aqueous Solution >> Mercapto Compound-2 (1- (3-methylureido) -5
-Mercaptotetrazole sodium salt) 20 g
It was dissolved in 80 g to give a 2.0% by mass aqueous solution.

<< Preparation of Pigment-1 Dispersion >> C.I. I. Pig
Meng Blue 60 (64 g) and Kao Corporation's Demol N (6.4 g) were added with 250 g of water and mixed well to form a slurry. 800 g of zirconia beads having an average diameter of 0.5 mm was prepared, placed in a vessel together with the slurry, and dispersed with a disperser (1/4 G sand grinder mill: manufactured by AIMEX Co., Ltd.) for 25 hours to obtain a pigment-1 dispersion. Obtained. The pigment particles contained in the thus obtained pigment dispersion had an average particle diameter of 0.21 μm.

<< Preparation of SBR Latex Liquid >> Tg = 22
The ° C SBR latex was prepared as follows. Using ammonium persulfate as a polymerization initiator and an anionic surfactant as an emulsifier, emulsion polymerization of 70.0 mass of styrene, 27.0 mass of butadiene and 3.0 mass of acrylic acid was carried out, followed by aging at 80 ° C. for 8 hours. It was Then 40
The mixture was cooled to 0 ° C., adjusted to pH 7.0 with aqueous ammonia, and SANDET BL manufactured by Sanyo Kasei Co., Ltd. was added so as to be 0.22%. Next, a 5% aqueous sodium hydroxide solution was added to adjust the pH to 8.3, and the pH was further adjusted with aqueous ammonia.
It was adjusted to be 8.4. Na ⁺ used at this time
The molar ratio of ions to NH ₄ ⁺ ions was 1: 2.3.
Further, 0.15 ml of a 7% aqueous solution of benzoisothiazoline nonone sodium salt was added to 1 kg of this liquid to prepare an SBR latex liquid.

(SBR latex: -St (70.0)
-Bu (27.0) -AA (3.0) -latex)
Tg22 ℃, average particle size 0.1μm, concentration 43 mass%, 25 ℃ 60% R
Equilibrium water content in H at 0.6% by mass, ionic conductivity 4.
2 mS / cm (Ion conductivity was measured by Toa Denpa Kogyo Co., Ltd. conductivity meter CM-30S, latex stock solution (43% by mass) was measured at 25 ° C.), and SBR latexes having different pH 8.4 Tg were measured. It can be prepared by a similar method by appropriately changing the ratio of styrene and butadiene.

<< Preparation of Emulsion Layer (Photosensitive Layer) Coating Solution-1 >>
1000 g of the organic silver salt dispersion obtained above, 276 ml of water,
Pigment-1 dispersion 33.2 g, organic polyhalogen compound-
24 dispersion 21 g, organic polyhalogen compound-1 dispersion 58 g, phthalazine compound-1 solution 173 g, SBR latex (Tg: 22 ° C.) liquid 1082 g, reducing agent complex-
1 dispersion 299 g, development accelerator-1 dispersion 6 g, mercapto compound-1 aqueous solution 9 ml, and mercapto compound-2 aqueous solution 27 ml were sequentially added, and a silver halide mixed emulsion A 117 g was added immediately before coating, and an emulsion layer was well mixed. The coating solution was sent to the coating die as it was and applied.

The viscosity of the emulsion layer coating solution was measured with a B-type viscometer of Tokyo Keiki Co., Ltd. at 40 ° C. (No. 1 rotor, 60 r).
It was 25 [mPa · s] in pm). The viscosity of the coating solution at 25 ° C. using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. was 230, 60, 46 at shear rates of 0.1, 1, 10, 100, 1000 [1 / sec], respectively. 24, 18 [mP
a · s]. The amount of zirconium in the coating solution is silver 1
It was 0.38 mg per gram.

<< Preparation of Emulsion Layer (Photosensitive Layer) Coating Solution-2 >>
1000 g of the organic silver salt dispersion obtained above, 276 ml of water,
Pigment-1 Dispersion 32.8 g, organic polyhalogen compound-
24 dispersion 21 g, organic polyhalogen compound-1 dispersion 58 g, phthalazine compound-1 solution 173 g, SBR latex (Tg: 20 ° C.) liquid 1082 g, reducing agent-2 dispersion 155 g, hydrogen bonding compound-1 dispersion 55 g , Development accelerator-1 dispersion 6 g, development accelerator-2 dispersion 2 g,
Development Accelerator-3 Dispersion 3 g, Color Tone Adjuster-1 Dispersion 2
g, mercapto compound-2 aqueous solution 6 ml are sequentially added,
Immediately before coating, 117 g of silver halide mixed emulsion A was added and well mixed, and the emulsion layer coating solution was directly sent to the coating die for coating.

The viscosity of the emulsion layer coating solution was measured with a B-type viscometer of Tokyo Keiki Co., Ltd. at 40 ° C. (No. 1 rotor, 60 r).
It was 40 [mPa · s] in pm). The viscosity of the coating solution at 25 ° C. using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. was 530, 144, 96 at shear rates of 0.1, 1, 10, 100, 1000 [1 / sec], respectively. 51, 28 [mP
a · s]. The amount of zirconium in the coating solution is silver 1
It was 0.25 mg per g.

<< Preparation of Emulsion Surface Intermediate Layer Coating Solution >> Polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.) 1000
g, 272 g of 5% by weight pigment dispersion, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization weight ratio 64/9/20/5/2), latex 19% by weight liquid 42
27 ml of a 5 mass% aqueous solution of aerosol OT (manufactured by American Cyanamid), 135 ml of a 20 mass% aqueous solution of diammonium phthalate salt, and a total amount of 100
Water was added to 00 g, and the pH was adjusted to 7.5 with NaOH to obtain a coating solution for the intermediate layer, which was 9.1 ml /
The solution was fed to the coating die so that the m ² was reached. The viscosity of the coating liquid is a B-type viscometer 40 ° C (No. 1 rotor, 60r
It was 58 [mPa · s] in pm).

<< Preparation of Coating Solution for First Layer of Emulsion Surface Protective Layer >> 64 g of inert gelatin was dissolved in water to prepare a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization weight ratio of 6).
4/9/20/5/2) latex 27.5 mass% liquid 8
0 g, 23% of 10 mass% methanol solution of phthalic acid
23 ml of a 10 mass% aqueous solution of 4-methylphthalic acid,
28 ml of 0.5 mol / L sulfuric acid, Aerosol O
5 ml of a 5% by mass aqueous solution of T (manufactured by American Cyanamid), 0.5 g of phenoxyethanol and 0.1 g of benzoisothiazolinone were added, and water was added so that the total amount became 750 g to prepare a coating solution, which was 4% by mass. Chrome alum 2
Immediately before coating, 6 ml of the mixture was mixed with a static mixer, and the mixture was fed to a coating die at 18.6 ml / m ² . The viscosity of the coating liquid is a B-type viscometer 40 ° C. (No. 1
It was 20 [mPa · s] at a rotor of 60 rpm.

<< Preparation of Coating Solution for Second Layer of Emulsion Surface Protective Layer >> 80 g of inert gelatin was dissolved in water to prepare a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization weight ratio of 6).
4/9/20/5/2) latex 27.5 mass% liquid 1
02 g, 3.2 ml of a 5 mass% solution of a fluorosurfactant (F-1: N-perfluorooctylsulfonyl-N-propylalanine potassium salt), a fluorosurfactant (F-2: polyethylene glycol mono ( N-perfluorooctylsulfonyl-N-propyl-2-aminoethyl) ether [ethylene oxide average degree of polymerization = 1
32 ml of 2% by mass aqueous solution of 5]), aerosol OT
(American Cyanamid Co., Ltd.) in a 5 mass% solution of 23
ml, fine particles of polymethylmethacrylate (average particle size of 0.
7 μm) 4 g, polymethylmethacrylate fine particles (average particle size 4.5 μm) 21 g, 4-methylphthalic acid 1.6
g, phthalic acid 4.8 g, 0.5 mol / L concentration of sulfuric acid 44
ml, benzoisothiazolinone 10mg total 650g
445 m of an aqueous solution containing 4% by mass of chromium alum and 0.67% by mass of phthalic acid by adding water so that
Immediately before coating, a mixture of 1 with a static mixer was used as a surface protective layer coating solution, and the solution was fed to a coating die at a rate of 8.3 ml / m ² . The viscosity of the coating liquid is 19 [mP with a B type viscometer at 40 ° C (No. 1 rotor, 60 rpm).
a · s].

<< Preparation of Photothermographic Material-A >> An antihalation layer coating solution was applied to the back side of the undercoat support so that the solid fine particle dye solid coating amount was 0.04 g / m ^2. Simultaneous multi-layer coating of the back surface protective layer coating solution to give a gelatin coating amount of 1.7 g / m ² , followed by drying,
A back layer was produced.

Samples of photothermographic materials were coated on the surface opposite to the back surface from the undercoat surface in the order of emulsion layer, intermediate layer, protective layer first layer, protective layer second layer by slide bead coating method. Was produced. At this time, the emulsion layer and the intermediate layer are 31
℃, the first protective layer is 36 ℃, the first protective layer is 37 ℃
The temperature was adjusted to. Coating amount of each compound in the emulsion layer (g /
m ² ) is as follows.

[0296] Silver behenate 5.55 Pigment (C.I.Pigment Blue 60) 0.036 Organic polyhalogen compound dispersion-24 0.12 Organic polyhalogen compound dispersion-1 0.37 Phthalazine compound-1 0.19 SBR latex 9.97 Reducing agent complex-1 1.41 Development accelerator-1 0.024 Mercapto compound-1 0.002 Mercapto compound-2 0.012 Silver halide (as Ag) 0.091

The coating and drying conditions are as follows. The coating is performed at a speed of 160 m / min, and the gap between the tip of the coating die and the support is 0.10 to 0.30 mm,
The pressure in the decompression chamber was set to be 196 to 882 Pa lower than the atmospheric pressure. Prior to coating, the support was neutralized with an ionic wind. In the subsequent chilling zone, the coating liquid was cooled with a wind having a dry-bulb temperature of 10 to 20 ° C., and then transported in a non-contact type, and a dry-bulb temperature of 23 to 45 ° C. in a tumble type non-contact drying device It was dried with a dry wind having a wet bulb temperature of 15 to 21 ° C. 25 after drying
After conditioning the humidity at 40 ° C to 60% RH at 70 ° C,
Heated to 90 ° C. After heating, the film surface was cooled to 25 ° C.

The matteness of the prepared photothermographic material was Bekk smoothness of 550 seconds on the side of the photosensitive layer and 13 on the back side.
It was 0 seconds. The pH of the film surface on the photosensitive layer surface side was measured and found to be 6.0.

<< Preparation of Photothermographic Material-B >> For photothermographic material-A, emulsion layer coating solution-1 was replaced with emulsion layer coating solution-
2, the yellow dye compound-1 was removed from the antihalation layer, and the fluorine-containing surfactants in the back surface protective layer and emulsion surface protective layer were changed to F-1, F-2, F-3 and F-4.
To F-5, F-6, F-7 and F-8, respectively, to prepare a photothermographic material-B in the same manner as the photothermographic material-A. The coating amount (g / m ² ) of each compound in the emulsion layer at this time is as follows.

[0300] Silver behenate 5.55 Pigment (C.I.Pigment Blue 60) 0.036 Organic polyhalogen compound-24 0.12 Organic polyhalogen compound-1 0.37 Phthalazine compound-1 0.19 SBR Latex 9.67 Reducing agent-2 0.81 Hydrogen-bonding compound-1 0.30 Development accelerator-1 0.024 Development accelerator-2 0.010 Development accelerator-3 0.015 Color tone adjuster-1 0.010 Mercapto compound-2 0.002 Silver halide (as Ag) 0.091

<< Preparation of Photothermographic Material-C-1 to C-24 >> A solid dispersion-1 of the organic polyhalogen compound in the emulsion layer coating liquid-1 was used in Example 1 with respect to the photothermographic material-A. In the same manner as in the heat-developable photosensitive material-A, except that the solid dispersion of the organic polyhalogen compound sampled from the bottom of the storage container was used for storage under the storage conditions shown in Table 1 (room temperature for 3 months). Materials-C-1 to C-24 were prepared.

<< Preparation of Photothermographic Materials-D-1 to D-24 >> A solid dispersion-1 of the organic polyhalogen compound in the emulsion layer coating liquid-1 was used in Example 1 with respect to the photothermographic material-B. In the same manner as in the photothermographic material B, except that the polyhalogen compound dispersion after storage under the storage conditions (room temperature 1 month) in Table 1 (using the lower part of the storage container) was used, D-1 to D-24 were produced.

The chemical structures of the compounds used in the examples of the present invention are shown below.

[0304]

[Chemical 21]

[0305]

[Chemical formula 22]

[0306]

[Chemical formula 23]

[0307]

[Chemical formula 24]

[0308]

[Chemical 25]

(Evaluation of Photographic Performance) Each of the obtained samples was cut into half-size pieces, packaged in the following packaging materials in an environment of 25 ° C. and 50% RH, stored at room temperature for 2 weeks, and then evaluated as follows. I went. The results are shown in Tables 3 and 4. (Packaging material) PET 10 μm / PE 12 μm / Aluminum foil 9 μm / Ny 15 μm / Polyethylene 50 μm containing 3% carbon. Oxygen permeability: 0 ml / atm · m ² · 25 ° C · day,
Moisture transmission rate: 0 g / atm · m ² · 25 ° C · day

The sample was set to exposure and heat development (112 ° C.-119 ° C.-121 ° C.-121 ° C.) with a Fuji Medical Dry Laser Imager FM-DPL (equipped with a 660 nm semiconductor laser with a maximum output of 60 mW (IIIB)). With four panel heaters, the photothermographic material-A and the photothermographic materials-C-1 to C-24 are 24 seconds in total, and the photothermographic material-B and the photothermographic materials-D-1 to D-24 are Total 1
4 seconds), and the obtained image was evaluated with a densitometer.

<Sensitivity> In Table 3, the photothermographic material-
In Table 4, relative sensitivity is shown with C-1 being the sensitivity of the photothermographic material-D-1 as 100. Relative sensitivity is 98-1
02 was set as the allowable range.

<Density> In Table 3, the photothermographic material-
In Table 4, the relative density of C-1 is shown with the maximum density of the photothermographic material-D-1 being 100. Relative concentration is 98
The allowable range was from 102 to 102.

<Surface> The light-sensitive material obtained by exposing the above coating material to light was thermally developed (about 120 ° C.), and streaks appearing in the obtained solid developed image were visually evaluated according to the following criteria. ◯: There are almost no coating stripes (two or less), and there is no practical problem. Δ: The number of coating stripes is 2 or more and 5 or less, which may cause a problem in practical use. X: The number of coating stripes is 5 or more, and there is a problem in practical use. In addition, ◯ was made into the allowable range.

[0314]

[Table 3]

[0315]

[Table 4]

As shown in Tables 3 and 4, the average sedimentation rate (v ₂₆ ) of the dispersoid at 26 ° C. was 5.0 × 10 ^-6 m
A solid dispersion of a polyhalogen compound having an average sedimentation velocity (v ₁₀ ) of the dispersoid of 2.5 × 10 ⁻⁶ mm / sec or less at m / sec or less and at 10 ° C. was used after aging. It can be seen that even when a photothermographic material is produced, a photothermographic material can be obtained in which variations in photographic sensitivity and density change are small and the surface condition is not deteriorated.

Example 3 Solid Dispersion Other than Polyhalogen Compound << Preparation of Reducing Agent Compounds 101 to 110 Dispersions >> In Example 2, instead of the reducing agent-2 of the reducing agent-2 dispersion, Table 5 was used. As shown in Table 5, the median diameter is changed by changing the dispersion time, and the viscosity of the dispersion is changed by changing the type and concentration of the reducing agent compound or the dispersing agent as shown in Table 5. Solid dispersions 101 to 110 of a reducing agent were prepared in the same manner as the reducing agent-2 dispersion except that the specific gravity of the dispersoid was changed by changing the type. Details of the solid dispersion of the reducing agent thus obtained [average sedimentation rate (v ₂₆ and v ₁₀ ), etc.] are shown in Tables 5 and 6.

[0318]

[Table 5]

[0319]

[Table 6]

As shown in Tables 5 and 6, the average sedimentation rate (v ₂₆ ) of the dispersoid at 26 ° C. was 5.0 × 10 ^-6 m
A solid dispersion of the reducing agent dispersion having an average sedimentation rate (v ₁₀ ) of the dispersoid of 2.5 × 10 ⁻⁶ mm / sec or less at m / sec or less and at 10 ° C. is a storage container after aging. It was found that the change in concentration was small and stable.

<< Preparation of Hydrogen Bonding Compound-201 to 210 Dispersion >> The hydrogen bonding compound shown in Table 7 was used in place of the hydrogen bonding compound-1 of Example 2, and the dispersion time was changed as shown in Table 7. By changing the median diameter by changing it, the viscosity of the dispersion can be changed by changing the type and concentration of the hydrogen-bonding compound or dispersant, and the specific gravity of the dispersoid can be changed by changing the type of the hydrogen-bonding compound. Hydrogen bonding compound dispersion-
In the same manner as in 1, the hydrogen-bonding compound dispersions 201 to 210 were dispersed. Details of solid dispersion of hydrogen-bonding compound thus obtained [median diameter, viscosity of solid dispersion (10 ° C. and 25 ° C.), specific gravity of dispersoid, average sedimentation rate of dispersoid (1
0 ° C. and 25 ° C.), etc.] are shown in Tables 7 and 8.

[0322]

[Table 7]

[0323]

[Table 8]

As shown in Tables 7 and 8, the average sedimentation velocity (v ₂₆ ) of the dispersoid at 26 ° C. was 5.0 × 10 ^-6 m
A solid dispersion of a hydrogen-bonding compound having an average sedimentation velocity (v ₁₀ ) of the dispersoid of 2.5 × 10 ⁻⁶ mm / sec or less at m / sec or less and at 10 ° C. is a storage container after aging. It was found that the change in concentration was small and stable.

Example 4 Photothermographic Material Using Solid Dispersion Other Than Polyhalogenate << Preparation of Photothermographic Materials -E-1 to E-10 >> Photothermographic Material-B, emulsion The reducing agent compound dispersion of Layer Coating Solution-1 was stored under the storage conditions of Tables 5 and 6 of Example 3 and the reducing agent compound dispersion was aged (the lower part of the storage container was used).
Photosensitive Photosensitive Materials-E-1 to E-10 were prepared in the same manner as the Photothermographic Material-B except that

<< Preparation of Photothermographic Materials-F-1 to F-10 >> Table 7 of Example 3 containing the hydrogen-bonding compound dispersion of Emulsion Layer Coating Solution-1 for Photothermographic Material-B. And the photothermographic material-F-1 to F in the same manner as the photothermographic material-B except that the hydrogen-bonding compound dispersion after storage under the storage conditions in Table 8 was used (the lower part of the storage container was used). -10 was produced. Evaluation of the photothermographic material was carried out in the same manner as in Example 2. The results are shown in Tables 9 and 10.

[0327]

[Table 9]

As shown in Table 9, the average sedimentation velocity (v ₂₆ ) of the dispersoid at 26 ° C. was 5.0 × 10 ^-6 mm / se.
c or less, and a solid dispersion of a reducing agent compound having an average sedimentation velocity (v ₁₀ ) of the dispersoid at 10 ° C. of 2.5 × 10 ⁻⁶ mm / sec or less was subjected to heat development using this after aging. It has been found that even when a photosensitive material is produced, a photothermographic material which is excellent in coated surface state and has little variation in photographic sensitivity and density change can be obtained.

[0329]

[Table 10]

As shown in Table 10, dispersion at 26 ° C.
Average sedimentation rate of quality (v₂₆) Is 5.0 × 10^-6mm / s
Average sedimentation rate of dispersoids below ec and at 10 ° C
(V _Ten) Is 2.5 × 10^-6Water that is less than mm / sec
The solid dispersion of the elementary binding compound was used with this after aging.
Even when a photothermographic material is prepared,
Excellent thermal development with less variation in photographic sensitivity and density changes
It has been found that a photosensitive material can be obtained.

[0331]

According to the present invention, a solid dispersion of a photographically useful compound excellent in stability over time and a method for storing the same, and
It is possible to provide a photothermographic material which is excellent in coated surface state and has good photographic sensitivity and density.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H123 AB00 AB03 AB23 AB28 BA00                       BA14 BB00 BB28 BC00 BC01                       BC11 CB00 CB03

Claims (14)

[Claims] 1. A solid dispersion of a photographically useful compound comprising a dispersoid composed of an organic compound and a dispersion medium, wherein the dispersoid has an average sedimentation rate at 25 ° C. represented by the following formula (1) ( v ₂₅ ) is 5.0 × 10 ⁻⁶ mm / sec or less, a solid dispersion of a photographically useful compound. In the formula ^{_{(1) v 25 = 2r 2}} g (ρs 25 -ρ 25) / 9η 25 [formula (1), r is the median diameter of the dispersoid, g is the gravitational acceleration, .rho.s ₂₅ specific gravity of the dispersoid at 25 ° C. , Ρ
₂₅ represents the specific gravity of the dispersion medium at 25 ° C., and η ₂₅ represents the viscosity of the dispersion at 25 ° C. ] 2. The specific gravity (ρ) of the dispersoid in the formula (1)
The solid dispersion of the photographically useful compound according to claim 1, wherein s ₂₅ ) is 1.1 or more. 3. The solid dispersion of the photographically useful compound according to claim 1, wherein the organic compound is a polyhalogen compound. 4. A method for storing a solid dispersion of a photographically useful compound, which comprises storing the solid dispersion of the photographically useful compound according to claim 1 at room temperature. 5. A solid dispersion of a photographically useful compound comprising a dispersoid composed of an organic compound and a dispersion medium, wherein the dispersoid has an average settling rate at 10 ° C. represented by the following formula (2) ( v ₁₀ ) is 2.5 × 10 ⁻⁶ mm / sec or less, a solid dispersion of a photographically useful compound. In equation ^{_{(2) v 10 = 2r 2}} g (ρs 10 -ρ 10) / 9η 10 [formula (2), r is the median diameter of the dispersoid, g is the gravitational acceleration, .rho.s ₁₀ specific gravity of the dispersoid at 10 ° C. , Ρ
₁₀ represents the specific gravity of the dispersion medium at 10 ° C, and η ₁₀ represents the viscosity of the dispersion at 10 ° C. ] 6. The specific gravity (ρ) of the dispersion medium in the formula (2)
The solid dispersion of the photographically useful compound according to claim 5, wherein s ₁₀ ) is 1.1 or more. 7. A solid dispersion of a photographically useful compound according to claim 5, wherein the organic compound is a polyhalogen compound. 8. A method for storing a solid dispersion of a photographically useful compound, which comprises storing the solid dispersion of the photographically useful compound according to claim 5 under refrigeration. 9. A photothermographic material having on a support at least one layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions, and a binder, said layer. And / or another layer provided on the support, a dispersoid composed of an organic compound, and a dispersion medium,
Is formed by applying and drying a coating liquid containing at least one solid dispersion of a photographically useful compound containing
Moreover, the average sedimentation velocity (v ₂₅ ) at 25 ° C. of the dispersoid represented by the following formula (1) is 5.0 × 10 ⁻⁶ mm / se.
A photothermographic material which is c or less. In the formula ^{_{(1) v 25 = 2r 2}} g (ρs 25 -ρ 25) / 9η 25 [formula (1), r is the median diameter of the dispersoid, g is the gravitational acceleration, .rho.s ₂₅ specific gravity of the dispersoid at 25 ° C. , Ρ
₂₅ represents the specific gravity of the dispersion medium at 25 ° C., and η ₂₅ represents the viscosity of the dispersion at 25 ° C. ] 10. The photothermographic material according to claim 9, wherein the dispersoid in the formula (1) has a specific gravity (ρs ₂₅ ) of 1.1 or more. 11. A photothermographic material comprising, on a support, at least one layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions and a binder, the layer and / Or another layer provided on the support, a dispersoid of an organic compound, and a dispersion medium,
Is formed by applying and drying a coating liquid containing at least one solid dispersion of a photographically useful compound containing
Moreover, the average sedimentation velocity (v ₁₀ ) of the dispersoid at 10 ° C. represented by the following formula (2) is 2.5 × 10 ⁻⁶ mm / se.
A photothermographic material which is c or less. In equation ^{_{(2) v 10 = 2r 2}} g (ρs 10 -ρ 10) / 9η 10 [formula (2), r is the median diameter of the dispersoid, g is the gravitational acceleration, .rho.s ₁₀ specific gravity of the dispersoid at 10 ° C. , Ρ
₁₀ represents the specific gravity of the dispersion medium at 10 ° C, and η ₁₀ represents the viscosity of the dispersion at 10 ° C. ] 12. The photothermographic material according to claim 11, wherein the dispersoid in the formula (2) has a specific gravity (ρs ₁₀ ) of 1.1 or more. 13. The photothermographic material according to claim 9, wherein the organic compound is a polyhalogen compound. 14. The binder is latex,
Moreover, the coating liquid is an aqueous coating liquid.
The photothermographic material according to any one of 1.